* Make `UnregisterProject` a request. This way the client-side project can wait
to clear out its remote id until the request has completed, so that the
contacts panel can avoid showing duplicate private/public projects in the
brief time after unregistering a project, before the next UpdateCollaborators
message is received.
* Remove the `RegisterWorktree` and `UnregisterWorktree` methods and replace
them with a single `UpdateProject` method that idempotently updates the
Project's list of worktrees.
Max Brunsfeld
d11beb3c02