Adds a facehugger_protection var to all hats.

Created by: gbasood

Only face-protecting hats will actually utilize this value. Rig suit helmets get a starting value of 8. All other hats get a starting value of 4. I'm willing to adjust these values before merging based on feedback. If you have any special snowflake hats you want me to buff, now's the time to mention them. Mask slot items still do nothing.

Every time a facehugger tries to rip off your mask, it will decrement this value by 1. If it hits 0 or less, facehuggers succeed in ripping it off.

Resolves #8214 (closed) although maybe not the way Celt wanted it to I guess? If we want an actual health var for helmets we can always change that but eh Fixes #8279 (closed)