[TrimmableTypeMap] Implement alias support in codegen and runtime

[simonrozsival]

Summary

Implement trimmable typemap alias support end-to-end, covering both generated metadata/code and runtime lookup/activation.

Scope

• generate alias entries and associations for duplicate JNI names
• resolve alias entries in TrimmableTypeMap / TrimmableTypeMapTypeManager at runtime
• add or update tests covering duplicate JNI mappings and alias activation

Context

This is the dedicated follow-up for the alias handling intentionally deferred during the current runtime-only rollout. The current implementation explicitly punts on typemap aliases and should be completed here.

Part of #10788.