We hold these locks for a short amount of time anyway, and using an
async lock could cause parallel sends to happen in an order different
than the order in which `send`/`request` was called.
Co-Authored-By: Nathan Sobo <nathan@zed.dev>
This will make it possible for us to render their avatars. Previously we only had the user ids. During rendering, everything needs to be available synchronously. So now, whenever collaborators are added, we perform the async I/O to fetch their user data prior to adding them to the worktree.
