[ci-fix] Fix Android NativeAOT template for updated memory safety rules

[simonrozsival]

Summary

• remove type-level unsafe modifiers that are invalid under the updated C# memory-safety rules
• add scoped unsafe blocks around JNI and native interop operations
• explicitly mark the pointer-bearing native declarations unsafe and document their caller safety contracts

This is closely related to #134134, which fixed the equivalent Apple NativeAOT build break. The Apple imports were correctly marked safe because they synchronously copy managed string inputs and impose no obligation on callers. The Android imports remain unsafe because the native implementations dereference or retain the supplied JavaVM* and argv pointers.

@matouskozak noticed the Android failure in runtime-extra-platforms build 1604366.

Validation

• ./build.sh tasks
• Android arm64 NativeAOT libraries and test APK build, using the CI command with /p:StripSymbols=false because the local environment does not have llvm-objcopy
  • built and published both System.Text.Json.SourceGeneration.Roslyn3.11.Tests and System.Text.Json.SourceGeneration.Roslyn4.4.Tests
  • completed with zero warnings and zero errors

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What changed in this PR

Updates the Android NativeAOT template for revised C# memory-safety rules.

Changes:

• Scopes JNI and pointer operations in unsafe blocks.
• Marks pointer-bearing native declarations unsafe.
• Removes obsolete type-level unsafe modifiers.

File	Description
src/​tasks/​AndroidAppBuilder/​Templates/​monodroid-nativeaot.cs	Applies updated unsafe-context and interop safety annotations.

[simonrozsival]

Closing as a duplicate of #134212, which predates this PR and implements the same updated memory-safety migration. #134115 tracks the Android NativeAOT build break.

Note

This comment was generated with GitHub Copilot.