Reorganize syntax tests

This commit...

1. adds dummy test file for `.hcl`
2. removes redundant tests from `.tfvars`
3. renames test files to `syntax_test_scope.*` for syntax tests

   It creates room for `syntax_test_symbols.*` or `syntax_test_reindent.*`.

Author: deathaxe

tests/syntax_test_scope.hcl

@@ -0,0 +1,4 @@
+# SYNTAX TEST "HCL.sublime-syntax"
+
+# Same as normal Terraform syntax, hence nothing special to test here.
+# <- source.hcl

tests/syntax_test_terraform.tf renamed to tests/syntax_test_scope.tf

@@ -0,0 +1,4 @@
+# SYNTAX TEST "Terraform-vars.sublime-syntax"
+
+# Same as normal Terraform syntax, hence nothing special to test here.
+# <- source.terraform-vars