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

docs/static/frigate-api.yaml

@@ -3200,6 +3200,7 @@ paths:
                 duration: 30
                 include_recording: true
                 draw: {}
+                pre_capture: null
       responses:
         "200":
           description: Successful Response
@@ -5002,6 +5003,12 @@ components:
             - type: "null"
           title: Draw
           default: {}
+        pre_capture:
+          anyOf:
+            - type: integer
+            - type: "null"
+          title: Pre Capture Seconds
+          default: null
       type: object
       title: EventsCreateBody
     EventsDeleteBody: