R1:f9192d07f2c7

Align web UI "Disable" and "Approve/Disapprove" flows with new "Can Disable Users" permission

Summary:
Depends on D19606. Ref T13189. See PHI642.

- Disabling/enabling users no longer requires admin. Now, you just need "Can Disable Users".
- Update the UI to appropriately show the action in black or grey depending on what clicking the button will do.
- For "Approve/Disapprove", fix a couple bugs, then let them go through without respect for "Can Disable Users". This is conceptually a different…