wip: Refactoring stix2 export & performance improvement
wip: Refactoring stix2 export & performance improvement

MISP/MISP,FIRSTdotorg/MISP,TheDr1ver/MISP,SteveClement/MISP,devnull-/MISP,FIRSTdotorg/MISP,devnull-/MISP,TheDr1ver/MISP,FIRSTdotorg/MISP,Rafiot/MISP,devnull-/MISP,MISP/MISP,FloatingGhost/MISP,SteveClement/MISP,MISP/MISP,devnull-/MISP,TheDr1ver/MISP,FloatingGhost/MISP,MISP/MISP,Rafiot/MISP,FloatingGhost/MISP,Rafiot/MISP,Rafiot/MISP,TheDr1ver/MISP,FIRSTdotorg/MISP,MISP/MISP,SteveClement/MISP,SteveClement/MISP,FloatingGhost/MISP,SteveClement/MISP