We now treat new files that have no content as not-dirty. This fixes the
git diff view when deleted files are present.
It also fixes a long-standing bug where `zed RAEDME` and then closing
the tab would prompt for "unsaved changes" when there were none.
Release Notes:
- Fixed a bug where closing an empty, named, file would warn about
unsaved content.
This adds a new version of the project diff editor to go alongside the
new git panel.
The basics seem to be working, but still todo:
* [ ] Fix untracked files
* [ ] Fix deleted files
* [ ] Show commit message editor at top
* [x] Handle empty state
* [x] Fix panic where locator sometimes seeks to wrong excerpt
Release Notes:
- N/A
Conrad Irwin