Enable RawSyntax validation and alternate token introspection in GitHub Actions

Author: ahoppen

.github/workflows/pull_request.yml

@@ -8,6 +8,13 @@ jobs:
   tests:
     name: Test
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
+    with:
+      linux_env_vars: |
+        SWIFTSYNTAX_ENABLE_RAWSYNTAX_VALIDATION=1
+        SWIFTPARSER_ENABLE_ALTERNATE_TOKEN_INTROSPECTION=1
+      windows_env_vars: |
+        SWIFTSYNTAX_ENABLE_RAWSYNTAX_VALIDATION=1
+        SWIFTPARSER_ENABLE_ALTERNATE_TOKEN_INTROSPECTION=1
   soundness:
     name: Soundness
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main