Polish PR
- [ ] Horizontal scrollbar for git panel
- [ ] Allow shift clicking a checkbox in any section to stage the whole
section
- [ ] Clean up design of no changes/pending push state in panel
- [x] Ensure checkbox placeholder dot is centered in the checkbox
- [x] Improve spacing between elements in git panel entries
- [x] Update git branch icon to match branch selector text when disabled
- [x] Truncate last commit message less aggressively in panel
- [x] Clean up new panel header design
- [x] Remove `_background` version control keys (backgrounds are derived
from the foreground colors)
### Previous message truncation:
Before:

After:

### Make branch icon match when menu is disabled
Before:

After:

Release Notes:
- N/A *or* Added/Fixed/Improved ...
---------
Co-authored-by: Cole Miller <cole@zed.dev>
Co-authored-by: Cole Miller <m@cole-miller.net>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
This PR updates the ui of the git panel. It removes the header from the
panel and unifies the repository, branch and commit controls in the
bottom section.
It also adds a secondary menu to the primary button giving access to a
variety of actions for managing local and remote changes:

Known issues (will be fixed in a later pr)
- Spinner showing git operation progress was removed, will be re-added
- Clicking expand with the panel editor focused will commit (due to
shared action name. Already tracked)
Before | After

(Also adds `component`, `linkme` to cargo-machete ignore as they are
used in the `IntoComponent` proc-macro and will always be incorrectly
flagged as unused)
Release Notes:
- N/A
---------
Co-authored-by: Cole Miller <m@cole-miller.net>
Co-authored-by: Cole Miller <53574922+cole-miller@users.noreply.github.com>
Co-authored-by: Cole Miller <cole@zed.dev>
This PR removes the `name` field from under `lib` in the `Cargo.toml`
file for the `panel` crate, as it isn't necessary.
Also removed it from `script/new-crate`.
Release Notes:
- N/A
- Adds the `panel` crate for defining UI shared between panels, like
common button and header designs, etc
- Starts to update the git ui to be more consistent with other panels
Release Notes:
- N/A