R1:a6a19ac72179

Move "Delete User" action to user profiles

Summary:
Ref T4065. The existence of two separate edit workflows for users is broadly confusing to administrators.

I want to unify user administration and improve administration of system agent accounts. Particularly, I plan to:

- Give administrators limited access to profile editing of system agents (e.g., change profile picture).
- Give administrators limited access to Settings for system agents.
- Broadly, move all the weird old special editing into…