R1:f69f53124ce9

Use typeaheads instead of checkbox lists for task status / priority

Summary:
Ref T4100.

This makes it slightly harder to choose, say, all priorities above X or all priorities except Y. We could add `open()`, `closed()`, `min()`, `max()`, and `not()` functions if there's a meaningful demand for them. I suspect some of these are maybe worthwhile while others aren't as worthwhile.

Test Plan: {F380058}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4100

Differential…