Remove scene grabbables/physics support

Scene grabbables support was reverted in the Hubs client due to bugs and is now only present for the Hubs Client's addons branch and its behavior graphs add-on.  This commit removes the scene grabbables and physics support from the main Blender add-on to maintain compatibility with the current Hubs Client.  A corresponding commit to the behavior graphs Blender add-on adds support for scene grabbables/physics back into the behavior graphs Blender add-on so that the functionality isn't lost and can be used there.

Reverts "Merge pull request #285 from MozillaReality/fix-import-error-reporting"

This reverts commit 7eb5656, reversing
changes made to 87074ec.

Reverts "Merge pull request #282 from MozillaReality/scene-grabbables"

This reverts commit 87074ec, reversing
changes made to 3712349.

addons/io_hubs_addon/components/definitions/ammo_shape.py

@@ -7,7 +7,7 @@
 class AmmoShape(HubsComponent):
     _definition = {
         'name': 'ammo-shape',
-        'display_name': 'Ammo Shape (deprecated)',
+        'display_name': 'Ammo Shape',
         'category': Category.OBJECT,
         'node_type': NodeType.NODE,
         'panel_type': [PanelType.OBJECT, PanelType.BONE],