Treat window deactivation as a focus change for the purpose of autosave

Fix autosave when closing a tab

Fix panic on paste when editing with auto-indent

Co-Authored-By: Max Brunsfeld <max@zed.dev>

Instead of accepting text as it's input by the user, we will read it
out of the edit operation after it gets sanitized by the buffer.

Line ending fixes

Fix crash when pasting text with CRLF line endings

* Moving the logic from Rope to text::Buffer makes it easier
  to keep the Rope in sync with the fragment tree.
* Removing carriage return characters is lossier, but is much
  simpler than incrementally maintaining the invariant that
  there are no carriage returns followed by newlines. We may
  want to do something smarter in the future.

Co-authored-by: Keith Simmons <keith@zed.dev>

Switch from line-and-character renderer to a direct grid renderer

Highlight matching bracket when newest selection head is on a bracket

Set up basic enviroment variables

Select the last worktree root when right-clicking below all project panel entries

Add application menu item to open default key bindings

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