Allow profile menus to be collapsed and expanded

Summary:
Ref T10054. I think this gets everything except:

• circles on icons;
• I spent ~15 minutes poking at animations but wasn't able to get anything that looked reasonable whatsoever.

Test Plan:

• Collapsed menus.
• Expanded menus.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10054

Differential Revision: https://secure.phabricator.com/D15056