Forking the DataDog .NET Tracer to seed the OTel .NET Auto-Instrument…

…ation-Agent.

This is a fork of the DataDog .NET Tracer (aka "in-process agent", aka "auto-instrumentation agent").
It acts as the initial seed for the official Open Telemetry .NET Tracer.

We are doing this by merging the current master of https://github.com/DataDog/dd-trace-dotnet into an empty master of https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation.
In addition, I cleaned up all auxiliary files not directly related to the product (e.g., demos, tools, vendor-specific integration tests and benchmarks, we well as others). We can add them in later from the original repo if the community requires.

Everything builds, all unit tests are passing.

.clang-format

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+---
+# We'll use defaults from the LLVM style, but with 4 columns indentation.
+BasedOnStyle: Google

.editorconfig

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+# EditorConfig is awesome:http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Don't use tabs for indentation.
+[*]
+indent_style = space
+# (Please don't specify an indent_size here; that has too many unintended consequences.)
+
+# Code files
+[*.{cs,csx,vb,vbx}]
+indent_size = 4
+insert_final_newline = true
+charset = utf-8
+
+# Xml project files
+[*.{csproj,vbproj,vcxproj,vcxproj.filters,proj,projitems,shproj}]
+indent_size = 2
+
+# Xml config files
+[*.{props,targets,ruleset,config,nuspec,resx,vsixmanifest,vsct}]
+indent_size = 2
+
+# JSON files
+[*.json]
+indent_size = 2
+
+# Dotnet code style settings:
+[*.{cs,vb}]
+# Sort using and Import directives with System.* appearing first
+dotnet_sort_system_directives_first = true
+# Avoid "this." and "Me." if not necessary
+dotnet_style_qualification_for_field = false:suggestion
+dotnet_style_qualification_for_property = false:suggestion
+dotnet_style_qualification_for_method = false:suggestion
+dotnet_style_qualification_for_event = false:suggestion
+
+# Use language keywords instead of framework type names for type references
+dotnet_style_predefined_type_for_locals_parameters_members = true:suggestion
+dotnet_style_predefined_type_for_member_access = true:suggestion
+
+# Suggest more modern language features when available
+dotnet_style_object_initializer = true:suggestion
+dotnet_style_collection_initializer = true:suggestion
+dotnet_style_coalesce_expression = true:suggestion
+dotnet_style_null_propagation = true:suggestion
+dotnet_style_explicit_tuple_names = true:suggestion
+
+# CSharp code style settings:
+[*.cs]
+# Prefer "var" everywhere
+csharp_style_var_for_built_in_types = true:suggestion
+csharp_style_var_when_type_is_apparent = true:suggestion
+csharp_style_var_elsewhere = true:suggestion
+
+# Prefer method-like constructs to have a block body
+csharp_style_expression_bodied_methods = false:none
+csharp_style_expression_bodied_constructors = false:none
+csharp_style_expression_bodied_operators = false:none
+
+# Prefer property-like constructs to have an expression-body
+csharp_style_expression_bodied_properties = true:none
+csharp_style_expression_bodied_indexers = true:none
+csharp_style_expression_bodied_accessors = true:none
+
+# Suggest more modern language features when available
+csharp_style_pattern_matching_over_is_with_cast_check = true:suggestion
+csharp_style_pattern_matching_over_as_with_null_check = true:suggestion
+csharp_style_inlined_variable_declaration = true:suggestion
+csharp_style_throw_expression = true:suggestion
+csharp_style_conditional_delegate_call = true:suggestion
+
+# Newline settings
+csharp_new_line_before_open_brace = all
+csharp_new_line_before_else = true
+csharp_new_line_before_catch = true
+csharp_new_line_before_finally = true
+csharp_new_line_before_members_in_object_initializers = true
+csharp_new_line_before_members_in_anonymous_types = true

.gitattributes

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+###############################################################################
+# Set default behavior to automatically normalize line endings.
+###############################################################################
+* text=auto
+
+# Set line endings to LF, even on Windows. Otherwise, execution within Docker fails.
+# See https://help.github.com/articles/dealing-with-line-endings/
+*.sh text eol=lf
+*.bash text eol=lf
+
+###############################################################################
+# Set default behavior for command prompt diff.
+#
+# This is need for earlier builds of msysgit that does not have it on by
+# default for csharp files.
+# Note: This is only used by command line
+###############################################################################
+#*.cs     diff=csharp
+
+###############################################################################
+# Set the merge driver for project and solution files
+#
+# Merging from the command prompt will add diff markers to the files if there
+# are conflicts (Merging from VS is not affected by the settings below, in VS
+# the diff markers are never inserted). Diff markers may cause the following 
+# file extensions to fail to load in VS. An alternative would be to treat
+# these files as binary and thus will always conflict and require user
+# intervention with every merge. To do so, just uncomment the entries below
+###############################################################################
+#*.sln       merge=binary
+#*.csproj    merge=binary
+#*.vbproj    merge=binary
+#*.vcxproj   merge=binary
+#*.vcproj    merge=binary
+#*.dbproj    merge=binary
+#*.fsproj    merge=binary
+#*.lsproj    merge=binary
+#*.wixproj   merge=binary
+#*.modelproj merge=binary
+#*.sqlproj   merge=binary
+#*.wwaproj   merge=binary
+
+###############################################################################
+# behavior for image files
+#
+# image files are treated as binary by default.
+###############################################################################
+#*.jpg   binary
+#*.png   binary
+#*.gif   binary
+
+###############################################################################
+# diff behavior for common document formats
+# 
+# Convert binary document formats to text before diffing them. This feature
+# is only available from the command line. Turn it on by uncommenting the 
+# entries below.
+###############################################################################
+#*.doc   diff=astextplain
+#*.DOC   diff=astextplain
+#*.docx  diff=astextplain
+#*.DOCX  diff=astextplain
+#*.dot   diff=astextplain
+#*.DOT   diff=astextplain
+#*.pdf   diff=astextplain
+#*.PDF   diff=astextplain
+#*.rtf   diff=astextplain
+#*.RTF   diff=astextplain

.github/ISSUE_TEMPLATE/bug_report.md

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+---
+name: Bug report
+about: Create a report to help us improve
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Runtime environment (please complete the following information):**
+- Instrumentation mode: [e.g. automatic with msi installer or manual with NuGet package]
+- Tracer version: [e.g. 1.0.0]
+- OS: [e.g. Windows Server 2012 R2 ]
+- CLR: [e.g. .NET Framework 4.6.2, .NET Core 2.1]
+
+**Additional context**
+Add any other context about the problem here.
+
+<!--
+NOTE: To contact our support team, see https://www.datadoghq.com/support/
+When contacting support, please include the information requested above.
+If possible, also include the tracer log files found (by default) in:
+Windows: %ProgramData%\Datadog .NET Tracer\logs\dotnet-profiler.log
+Linux: /var/log/datadog/dotnet/dotnet-profiler.log
+--!>

.github/ISSUE_TEMPLATE/feature_request.md

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+---
+name: Feature request
+about: Suggest an idea for this project
+
+---
+
+**Are you requesting automatic instrumentation for a framework or library? Please describe.**
+- Framework or library name : [e.g. `ASP.NET MVC`, `StackExchange.Redis`]
+- Library type: [e.g. web framework, data store, cache]
+- Library version: [e.g. 5.2]
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/pull_request_template.md

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+Fixes #
+
+Changes proposed in this pull request:
+
+
+
+
+@DataDog/apm-dotnet