fix: [stix2 import] Fixed external pattern types parsing
fix: [stix2 import] Fixed external pattern types parsing

- Avoiding issues with patterns containing parts
  within brackets and separated by OR statements
  giving results like "[file" instead of "file"

MISP/MISP,MISP/MISP,SteveClement/MISP,SteveClement/MISP,SteveClement/MISP,MISP/MISP,MISP/MISP,MISP/MISP,SteveClement/MISP,SteveClement/MISP