R1:d3c325c4fc73

Allow objects to be put in an "MFA required for all interactions" mode, and support "MFA required" statuses in Maniphest

Summary:
Depends on D19898. Ref T13222. See PHI873. Allow objects to opt into an "MFA is required for all edits" mode.

Put tasks in this mode if they're in a status that specifies it is an `mfa` status.

This is still a little rough for now:

- There's no UI hint that you'll have to MFA. I'll likely add some hinting in a followup.
- All edits currently require MFA, even…