R1:6aee862bbe6a

Use ApplicationSearch in Differential

Summary:
Ref T603. Ref T2625. Fixes T3241. Depends on D5451. Depends on D6346.

@wez, this changes the Differential revision list UI substantially and may generate a lot of bikeshedding / who-moved-my-cheese churn. See T3417 for context, for example. The motivations for this change are:

- The list now works on devices, like phones and tablets. This is a requirement to make the rest of Differential work on devices.
- Although ApplicationSearch intentionally…