Allow API Events to be Detections or Alerts, depending on the Event Label (#21923)

* - API created events will be alerts OR detections, depending on the event label, defaulting to alerts
- Indefinite API events will extend the recording segment until those events are ended
- API event start time is the actual start time, instead of having a pre-buffer of record.event_pre_capture

* Instead of checking for indefinite events on a camera before deciding if we should end the segment, only update last_detection_time and last_alert_time if frame_time is greater, which should have the same effect

* Add the ability to set a pre_capture number of seconds when creating a manual event via the API. Default behavior unchanged

* Remove unnecessary _publish_segment_start() call

* Formatting

* handle last_alert_time or last_detection_time being None when checking them against the frame_time

* comment manual_info["label"].split(": ")[0] for clarity

frigate/api/defs/request/events_body.py

@@ -41,6 +41,7 @@ class EventsCreateBody(BaseModel):
     duration: Optional[int] = 30
     include_recording: Optional[bool] = True
     draw: Optional[dict] = {}
+    pre_capture: Optional[int] = None
 
 
 class EventsEndBody(BaseModel):