Add object filter ratio (#2952)

* Add object ratio config parameters

Issue: #2948

* Add config test for object filter ratios

Issue: #2948

* Address review comments

- Accept `ratio` default
- Rename `bounds` to `box` for consistency
- Add migration for new field

Issue: #2948

* Fix logical errors

- field migrations require default values
- `clipped` referenced the wrong index for region, since it shifted
- missed an inclusion of `ratio` for detections in `process_frames`
- revert naming `o[2]` as `box` since it is out of scope!

This has now been test-run against a video, so I believe the kinks are
worked out.

Issue: #2948

* Update contributing notes for `make`

Issue: #2948

* Fix migration

- Ensure that defaults match between Event and migration script
- Deconflict migration script number (from rebase)

Issue: #2948

* Filter objects out of ratio bounds

Issue: #2948

* Update migration file to 009

Issue: #2948

frigate/models.py

@@ -20,6 +20,7 @@ class Event(Model):
     box = JSONField()
     area = IntegerField()
     retain_indefinitely = BooleanField(default=False)
+    ratio = FloatField(default=1.0)
 
 
 class Recordings(Model):