R1:7db362a4b652

Cheat my way through the rest of the typeahead datasources

Summary:
Ref T5750. These are a pain to modernize and most don't matter, so cheat:

- Mark a bunch nonbrowsable, including some that probably should be browsable but which I don't want to deal with for now.
- For static datasources, add an easy server-side filter (this isn't really cheating, and is appropriate for the status/priority/application datasources).
- Make composite sources browsable if their components are browsable.

Test Plan…