add: [stix2 import] Parsing external network-traffic patterns
add: [stix2 import] Parsing external network-traffic patterns

- Code duplication is also avoided in attributes
  creation, since the only change is the mapping
  dictionary we can use the same function with
  only that parameter changing instead of having
  the same function multiple times

FloatingGhost/MISP,Rafiot/MISP,FIRSTdotorg/MISP,FloatingGhost/MISP,MISP/MISP,MISP/MISP,Rafiot/MISP,devnull-/MISP,SteveClement/MISP,FIRSTdotorg/MISP,SteveClement/MISP,SteveClement/MISP,Rafiot/MISP,Rafiot/MISP,FloatingGhost/MISP,SteveClement/MISP,devnull-/MISP,devnull-/MISP,FloatingGhost/MISP,devnull-/MISP,SteveClement/MISP,MISP/MISP,FIRSTdotorg/MISP,MISP/MISP,MISP/MISP,FIRSTdotorg/MISP