UI: Add reset to default value to keymap

With all the work on DNA defaults for 2.91, it's nice to expose this
convenient operator. This was already hardcoded in the UI code to the
backspace key, adding it to the keymap instead will make the shortcut
automatically show in the button right click menu.

Differential Revision: https://developer.blender.org/D9219

release/scripts/presets/keyconfig/keymap_data/blender_default.py

@@ -715,6 +715,7 @@ def km_user_interface(_params):
         ("anim.driver_button_remove", {"type": 'D', "value": 'PRESS', "ctrl": True, "alt": True}, None),
         ("anim.keyingset_button_add", {"type": 'K', "value": 'PRESS'}, None),
         ("anim.keyingset_button_remove", {"type": 'K', "value": 'PRESS', "alt": True}, None),
+        ("ui.reset_default_button", {"type": 'BACK_SPACE', "value": 'PRESS'}, {"properties": [("all", True)]}),
     ])
 
     return keymap