[Android] Add method metadata report API in Module.java

[kirklandsign]

🚀 The feature, motivation and pitch

Purpose: For feature parity as python runtime, and maybe users will need the metadata to check for inputs, or do test automation.

In

executorch/extension/android/executorch_android/src/main/java/org/pytorch/executorch/Module.java

Line 43 in 1432243

, add a new API like listMethods()

We will need a new Method.java as well, to save some metadata.

Alternatives

No response

Additional context

No response

RFC (Optional)

No response

cc @cbilgin