[grpc_clients] Accept PlatformMetadata when creating client
Summary:
- Updated grpc_clients::get_auth_client and get_unauthenticated_client to accept
PlatformMetadata argument instead of separate values for code version and platform.
- Updated all callsites across repo
Depends on D12282
Test Plan:
- CI
- Keyserver, native_rust_library, commtest compilation
- Performed several identity actions on clients (native + web) - printed metadata values server-side
Reviewers: varun, marcin
Reviewed By: marcin
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D12283