R1:ecd4dd4e0b08

Expose column positions via maniphest.edit

Summary: Ref T5214. Fixes T10486. Ref T6027. This exposes the `TYPE_COLUMNS` transaction in a usable way via API, and fixes the interactions via prefilling.

Test Plan:
- Created tasks directly into columns via API.
- Moved tasks between columns via API.
- Used `?column=...` to try to create a template task with valid and bogus column PHIDs.

Reviewers: chad

Reviewed By: chad

Subscribers: AmyLewis

Maniphest Tasks: T5214, T6027, T10486

Differential…