Outliner: Allow deleting entire selection

This allows deleting both collections and objects in the outliner
selection at the same time. This only works using the keyboard shortcuts
(X or Delete).

While this works, a more robust solution should be implemented later to
allow deleting the whole selection from the context menu as well.

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

@@ -787,6 +787,8 @@ def km_outliner(params):
         ("outliner.collection_new", {"type": 'C', "value": 'PRESS'}, None),
         ("outliner.collection_delete", {"type": 'X', "value": 'PRESS'}, None),
         ("outliner.collection_delete", {"type": 'DEL', "value": 'PRESS'}, None),
+        ("outliner.object_operation", {"type": 'X', "value": 'PRESS'}, {"properties": [("type", 'DELETE')]}),
+        ("outliner.object_operation", {"type": 'DEL', "value": 'PRESS'}, {"properties": [("type", 'DELETE')]}),
         ("object.move_to_collection", {"type": 'M', "value": 'PRESS'}, None),
         ("object.link_to_collection", {"type": 'M', "value": 'PRESS', "shift": True}, None),
         ("outliner.collection_exclude_set", {"type": 'E', "value": 'PRESS'}, None),

source/blender/editors/space_outliner/outliner_collections.c

@@ -346,7 +346,9 @@ static int collection_delete_exec(bContext *C, wmOperator *op)
     WM_msg_publish_rna_prop(mbus, &scene->id, view_layer, LayerObjects, active);
   }
 
-  return OPERATOR_FINISHED;
+  /* Temporary fix to allow deleting both collections and objects at the same time
+   * using the same key mapping. */
+  return OPERATOR_PASS_THROUGH;
 }
 
 void OUTLINER_OT_collection_delete(wmOperatorType *ot)