Fix broken selection behavior in multiple editors right after saving

Steps to recreate were:
* Open a Node Editor, add some nodes
* Save the file
* Select all nodes (A)
* Save it again, but with Ctrl+S
* Try to select an already selected node
It's supposed to deselect other nodes now, but for as long as the report
banner is shown in the status-bar ('Saved "foo.blend"'), this doesn't
work.

Also happened in the VSE, Dopesheet, NLA or everywhere else we recently
added drag-all-selected support to.

Issue was in there since 2.80. Basically the timer event sent by the
report banner broke assumptions in the selection operator.

Hope this fix doesn't have any side effects. Checked with Bastien
(initial author of this logic), but seems things are fine.

source/blender/windowmanager/intern/wm_operators.c

@@ -784,7 +784,7 @@ int WM_generic_select_modal(bContext *C, wmOperator *op, const wmEvent *event)
     }
   }
 
-  return OPERATOR_FINISHED | OPERATOR_PASS_THROUGH;
+  return OPERATOR_RUNNING_MODAL | OPERATOR_PASS_THROUGH;
 }
 
 int WM_generic_select_invoke(bContext *C, wmOperator *op, const wmEvent *event)