Rough initial cut of profile new profile menu

Summary:
Ref T10054. I haven't done any of the big-picture layout stuff yet, but this should get look-and-feel somewhere in the ballpark of reasonablness, I think.

Major missing stuff:

• No "collapse" state or action yet.
• Menu is not full-height (requires changes to the rendering pipeline).

Test Plan:

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10054

Differential Revision: https://secure.phabricator.com/D15016