fix: Block the addition of same type/category/value attributes in one shot to the same event
fix: Block the addition of same type/category/value attributes in one shot to the same event

- via the /events/add api

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