git: Git Panel UI, continued

[iamnbutler]

TODO:

• Investigate incorrect hit target for stage all button
• Add top level context menu
• Add entry context menus
• Show paths in list view
• For now, enter can just open the file
• 🐞: Hover deadzone in list caused by scrollbar
• 🐞: Incorrect status/nothing shown when multiple worktrees are added

---

This PR continues work on the feature flagged git panel.

Changes:

• Defines and wires up git panel actions & keybindings
• Re-scopes some actions from git_ui -> git.
  • General git actions (StageAll, CommitChanges, ...) are scoped to git.
  • Git panel specific actions (Close, FocusCommitEditor, ...) are scoped to `git_panel.
• Staging actions & UI are now connected to git!
• Unify more reusable git status into the GitState global over being tied to the panel directly.
• Uses the new git status codepaths instead of filtering all workspace entries

Release Notes:

• N/A