Acid protection for Biosuits, Ninja, and DeathSquad

- Biosuits, Ninja armor, and Deathsquad armor are now immune to acid.
- Deathsquad armor is now also fireproof!
Merge pull request #6212 from GunHog/DS_Ninja_Biosuit_Anti-acid

Acid immunity for Biosuits, Ninja, and DeathSquad, and fire protection for DeathSquad