PyAPI: Use annotations for RNA definitions

- Logical use of fields since they define type information.
- Avoids using ordered-dict metaclass.

Properties using regular assignments will print a warning and load,
however the order is undefined.

release/scripts/startup/bl_operators/clip.py

@@ -133,7 +133,7 @@ class CLIP_OT_filter_tracks(bpy.types.Operator):
     bl_idname = "clip.filter_tracks"
     bl_options = {'UNDO', 'REGISTER'}
 
-    track_threshold = FloatProperty(
+    track_threshold: FloatProperty(
         name="Track Threshold",
         description="Filter Threshold to select problematic tracks",
         default=5.0,