Removes ninja mask, fixes ninja internals, fixes non-ninja voice changer

As in title.

Non-ninja voice changer now has verbs to toggle and set the voice.
Ninjas now do not start with disabled internals.
Ninja mask removed; its functionality is entirely duplicated by the ninja rig now.

Fixes #7465.
Notice is blue: https://github.com/Baystation12/Baystation12/blob/master/code/stylesheet.dm#L57