feat(go): implement grpc stub generation

[ayush00git]

Why?

Go implementation only provides type generation and misses the gRPC service stub generations for now. this PR adds it.

Related issues

Closes #3274

What it does ?

Implemented till now -

ImportTracker class in base.py

1. which returns the foreign imports defined in a RpcMethod inside a schema file's service interface.

generate_services()

1. which returns a service generated file
2. License header, package header using get_package_name()
3. the imports block of go using _build_import_block(tracker)
_build_import_block(tracker) function returns the import block with fixed grpc, context imports which are required by every single generated file for each service. and a foreign type imports statement returned by the tracker.go_imports(). at end after all the service code generation is done, this function inserts the import block to the saved placeholder index.

• Substantial AI assistance was used in this PR: yes / no
• If yes, I included a completed AI Contribution Checklist in this PR description and the required AI Usage Disclosure.
• If yes, my PR description includes the required ai_review summary and screenshot evidence of the final clean AI review results from both fresh reviewers on the current PR diff or current HEAD after the latest code changes.

Does this PR introduce any user-facing change?

• Does this PR introduce any public API change?
• Does this PR introduce any binary protocol compatibility change?

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