Fixes an issue that caused Windows to fail when removing extension's
directories, as Zed had never stop any related processes.
Now:
* Zed shuts down and waits until the end when the language servers are
shut down
* Adds `impl Drop for WasmExtension` where does
`self.tx.close_channel();` to stop a receiver loop that holds the "lock"
on the extension's work dir.
The extension was dropped, but the channel was not closed for some
reason.
* Does more unregistration to ensure `Arc<WasmExtension>` with the `tx`
does not leak further
* Tidies up the related errors which had never reported a problematic
path before
Release Notes:
- N/A
---------
Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>
Co-authored-by: Smit <smit@zed.dev>
c6603e4fba