Summary:
Ref T13516. Minor improvements here:

  - Show key commands in the "View Options" dropdown.
  - Organize it slightly better.
  - Improve disabled item behaviors a little bit.
  - Add a "Browse Directory" action.
  - Rename "...in Diffusion" to "...in Repository".
  - Make "d", "D", and "h" use the same targeting rules as "\".
  - When you hide a file with the "h" menu item, select it.

Test Plan: Poked at the menu a lot, ran into less questionable behavior.

Maniphest Tasks: T13516

Differential Revision: https://secure.phabricator.com/D21160