Implement re_grpc_server

[jprochazk]

Related

• Closes Implement re_grpc_server #8451

What

This PR introduces a new gRPC service which behaves similarly to our existing TCP and WS comms.

• Any messages logged via the WriteMessages rpc will be stored in a buffer, and broadcast to all callers of ReadMessages.
• Any calls to ReadMessages will also yield the full history.
• If the buffer fills up beyond server_memory_limit, then messages are dropped in oldest first order (FIFO).

TODO:

• Use a SizeBytes impl in re_protos to measure size of stored messages instead of approximating via Message::encoded_len
• Add a test for the memory limit

[github-actions]

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Result	Commit	Link	Manifest
✅	f59825a	https://rerun.io/viewer/pr/8622	+nightly +main

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