Add Differential keyboard shortcuts for "mark done" and "hide/show"

Summary:
Fixes T8130. Allows selected comments to be shown/hidden (with "q") or marked done/not-done (with "w").

(These key selections are because "qwer" are right next to each other on QWERTY keyboards, and now mean "hide, done, edit, reply".)

Also, allow "N" and "P" to do next/previous inline, including hidden inlines. This makes "q" to hide/show a little more powerful and a little easier to undo.

Test Plan: Used "q", "w", "N" and "P" to navigate and interact with comments.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T8130

Differential Revision: https://secure.phabricator.com/D17906