Adds streaming RPC forwarding to collab so guests can call
`GetInitialGraphData` and `SearchCommits` against a remote host project.
Previously these requests had no forwarder registered on the server and
would fail when invoked by a guest.
This mirrors the existing single-response forwarding pattern with new
analogues:
- `StreamResponse<R>` + `MessageContext::forward_request_stream`
- `Server::add_request_stream_handler`
- `forward_read_only_project_stream_request`, registered for both
messages
Also hardens both the unary and stream handlers to send
`respond_with_error` when a handler returns `Ok` without sending/ending
a response, so the client doesn't hang waiting for a reply that will
never arrive.
I added git graph collab integration tests for this as well.
Self-Review Checklist:
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable
Closes#55954
Release Notes:
- N/A
Anthony Eid
7277654c40