chg: [UI] Add icon for undefined threat level
chg: [UI] Add icon for undefined threat level

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