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/object_align.py

@@ -363,7 +363,7 @@ class AlignObjects(Operator):
     bl_label = "Align Objects"
     bl_options = {'REGISTER', 'UNDO'}
 
-    bb_quality = BoolProperty(
+    bb_quality: BoolProperty(
         name="High Quality",
         description=(
             "Enables high quality calculation of the "
@@ -372,7 +372,7 @@ class AlignObjects(Operator):
         ),
         default=True,
     )
-    align_mode = EnumProperty(
+    align_mode: EnumProperty(
         name="Align Mode:",
         description="Side of object to use for alignment",
         items=(
@@ -382,7 +382,7 @@ class AlignObjects(Operator):
         ),
         default='OPT_2',
     )
-    relative_to = EnumProperty(
+    relative_to: EnumProperty(
         name="Relative To:",
         description="Reference location to align to",
         items=(
@@ -393,7 +393,7 @@ class AlignObjects(Operator):
         ),
         default='OPT_4',
     )
-    align_axis = EnumProperty(
+    align_axis: EnumProperty(
         name="Align",
         description="Align to axis",
         items=(