Add Ongoing Attacker Activity Outcome to Incident Core Extension

[dc3-tsd]

1. Added 'ongoing' to activity-outcome-enum to better capture data for ongoing incidents.
2. Removed outdated language from attacker_activity.pattern_ref
3. Fixed error in JSON schema where kill_chain_phases were not included in attacker_activities
4. Fixed error in the incident duplication example where one or two incidents in the example had not had the value updated to match the current enumeration.
5. Added examples of kill_chain_phases within attacker activities.