Introduce autosave

Transmit new line ending when buffer is reloaded

Recalculate Metal layer's drawable size when window's scale factor changes

Handle files with CRLF (windows-style) line endings

Delete the autoclosing bracket when deleting the opening bracket

Support hitting enter on numpad

Improve user activity tracking

Fix problems that arise when large numbers of files change on disk

Update terminal to use the editor's cursor rendering and fix a couple bugs

Fix Zombie Language Servers

Changing the frequency at which we update worktrees highlighted a
problem in the randomized tests that was causing clients to receive
a definition to a worktree *before* observing the registration of
the worktree itself. This was most likely caused by #1224 because
the scenario that pull request enabled was the following:

- Guest requests a definition pointing to a non-existant worktree
- Server forwards the request to the host
- Host sends an `UpdateProject` message
- Host sends a response to the definition request
- Server observes the `UpdateProject` message and tries to acquire
  the store
- Given that we're waiting, the server goes ahead to process the
  response for the definition request, responding *before*
  `UpdateProject` is forwarded
- Server finally forwards `UpdateProject` to the guest

This commit ensures that, after forwarding a project request and getting a
response, we acquire a lock to the store again to ensure the project still
exists. This has the effect of ordering the forwarded request *after* any
message that was received prior to the response and for which we are still
waiting to acquire a lock to the store.

Whoopsies

This pull request is small and doesn't include many changes to any existing functionality. In the interest of removing blockers ASAP, I will merge.