This PR is an internal refactor in preparation for remote editing. It
restructures the public interface of `Worktree`, reducing the number of
call sites that assume that a worktree is local or remote.
* The Project no longer calls `worktree.as_local_mut().unwrap()` in code
paths related to basic file operations
* Fewer code paths in the app rely on the worktree's `LocalSnapshot`
* Worktree-related RPC message handling is more fully encapsulated by
the `Worktree` type.
to do:
* [x] file manipulation operations
* [x] sending worktree updates when sharing
for later
* opening buffers
* updating open buffers upon worktree changes
Release Notes:
- N/A
e174f16d50