R1:c8583b016daf

When workflow dialog buttons are clicked, disable the button

Summary:
Depends on D19245. Fixes T11145. Ref T13108. See PHI488. Disable workflow buttons when they're clicked to prevent accidental client-side double submission.

This might have some weird side effects but we should normally never need to re-use a workflow dialog form so it's not immediately obvious that this can break anything.

Test Plan:
- Added `sleep(1)` to the Mute controller and the Maniphest task controller.
- Added `phlog(...)`…