Remove transfer_fingerprint_to in favor of add_fingerprint

Add_fingerprint has sanity checks, which makes it a superior proc.
This fixes at the very least:
The following runtime has occured 14 time(s).
runtime error: Cannot execute null.Copy().
proc name: transfer fingerprints to (/atom/proc/transfer_fingerprints_to)
  source file: detective_work.dm,155
  usr: Engineering Cyborg-743 (/mob/living/silicon/robot)
  src: the disposal pipe (/obj/structure/disposalpipe/segment)