FEAT: Ability to set sub labels for specific events (#2949)

* Add sub label to model and set / delete funs

* Add migrations for sub label

* Tweaks to API and model

* Show sublabel if available

* Cleanups

* Update docs

* Show person in UI title

* Fix typo and don't fail on no json

* Transfer sub labels for in progress events

* Remove sublabel reset

* Remove person only check

* Make default null

* Update docs and formatting

* Make default null

* Make nullable in migration

* Undo null

* Update model to accept null

* Update migration to accept null

* Don't set to default values

* Remove redundant defaults and update http logic

* Only need a single route

* Enforce 20 character limit in http

* Update docs to mention 20 character limit

* Cleanup

* Separate insert and update to make sure updated values are retained when event ends

* Use insert instead of replace

* Remove redundant if and have should_update_db include clip or snapshot requirement.

frigate/models.py

@@ -6,6 +6,7 @@ from playhouse.sqlite_ext import *
 class Event(Model):
     id = CharField(null=False, primary_key=True, max_length=30)
     label = CharField(index=True, max_length=20)
+    sub_label = CharField(max_length=20, null=True)
     camera = CharField(index=True, max_length=20)
     start_time = DateTimeField()
     end_time = DateTimeField()