Migrate NailgunKillall and Provides to new options.

Also fix a few bugs in Provides that cropped up while testing.

Testing Done:
Tested various flag combos.

CI baking.

Reviewed at https://rbcommons.com/s/twitter/r/1212/
Sync of https://github.com/pantsbuild/pants/commit/7793a328b5fc354b314fac4722f7dcdf958dad9c