Cyber limbs fixes [FIXES #1920] + [Fixes #2180] + [RUNTIME FIX]

- Fixes the damage_converter.dm symptom trying to heal robotic limbs, Fixes #1920 
- Adds some NEEDED sanity checks to attempt_initiate_surgery (certain human only procs were being called on monkeys/other mobs)
- Merges the two organ healing procs.