R1:fe7e288cf558

Solidify PHUITwoColumnView as a page layout

Summary:
Rolls out a new "Object Page" design with PHUITwoColumnView. This is reasonably polished, but wanted to post it up for you now for feedback before chasing down minor bugs. This implements TwoColumn in the following applications:

- Ponder
- Paste
- Slowvote
- Countdown
- Projects
- Profile
- Passphrase

This helped track down display issues and inconsistencies and make sure the layout was flexible for different pages.

Test Plan:
Test each of the…