R1:8cf56913d8ef

Deprecate "user.enable" and "user.disable" API methods, redefine them in terms of "user.edit"

Summary:
Depends on D19604. Ref T13189. See PHI642. Deprecates these in favor of "user.edit", redefines them in terms of it, and removes the old `disableUser()` method.

I kept the "is admin" permissions check for consistency, since these methods have always said "(admin only)". This check may not be the most tailored check soon, but we can just keep executing it in addition to the real check.

For now, this…