feat: add /version endpoint and global X-Minder-Version header

[DharunMR]

Summary

This PR addresses the need to easily expose the Minder server's build version and commit hash for tooling and debugging purposes, as requested. It introduces a dedicated, unauthenticated /api/v1/version endpoint and adds a global gRPC Unary Interceptor to stamp the server version on all incoming HTTP/gRPC responses.

• Fixes Add a "/version" endpoint for Minder server #4048

Changes Included

• Protobuf: Added GetVersion RPC to HealthService mapped to GET /api/v1/version. Configured rpc_options to allow unauthenticated access (TARGET_RESOURCE_NONE).
• Server Handler: Implemented the GetVersion logic to return constants.CLIVersion and constants.Revision.
• Global Header: Created VersionHeaderInterceptor to inject the X-Minder-Version header into the response metadata for all requests.
• Telemetry Fix: Replaced the hardcoded "v0.1.0" service version in initMetrics with the dynamic constants.CLIVersion.

How I Tested This

1. Verified the new endpoint returns the correct JSON payload and header:
   curl -i http://localhost:8080/api/v1/version
2. Verified that the global header is successfully injected into other pre-existing endpoints:
   curl -I http://localhost:8080/api/v1/health

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[coveralls]

coverage: 59.402% (+0.01%) from 59.39% — DharunMR:add-version-endpoint into mindersec:main