chore(join/function): Add tests to signature-contains

[kakkoyun]

Adds flexible function signature matching to support partial and order-independent type matching.

This enables simpler instrumentation configuration when targeting functions that share common types (e.g. context.Context or error) regardless of their position or other parameters.

The change simplifies instrumentation configuration by reducing the need for multiple matchers when targeting related function groups

Changes

• Added SignatureContains matcher that checks for presence of types anywhere in function signatures
• Supports matching on partial argument/return types without requiring exact matches
• Added tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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Report is 1 commits behind head on eliottness/signature-contains.

Additional details and impacted files

@@                       Coverage Diff                        @@
##             eliottness/signature-contains     #582   +/-   ##
================================================================
  Coverage                                 ?   70.00%           
================================================================
  Files                                    ?      108           
  Lines                                    ?     7310           
  Branches                                 ?        0           
================================================================
  Hits                                     ?     5117           
  Misses                                   ?     1682           
  Partials                                 ?      511           

Components	Coverage Δ
Generators	80.24% <ø> (?)
Instruments	∅ <ø> (?)
Go Driver	76.51% <ø> (?)
Toolexec Driver	70.99% <ø> (?)
Aspects	77.55% <100.00%> (?)
Injector	76.78% <100.00%> (?)
Job Server	69.18% <ø> (?)
Other	70.00% <100.00%> (?)

Files with missing lines	Coverage Δ
internal/injector/aspect/join/function.go	73.23% <100.00%> (ø)

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