Fix T84493 issue with selection after boolean.

According to Blender selection rules, selections should be flushed
to containing elements. Added an EDMB_select_flush() after edit
mode booleans or intersects are done. Hopefully this doesn't break
any scripts that might have been depending on the old (broken) behavior.

source/blender/editors/mesh/editmesh_intersect.c

@@ -114,6 +114,7 @@ static void edbm_intersect_select(BMEditMesh *em, struct Mesh *me, bool do_selec
         }
       }
     }
+    EDBM_select_flush(em);
   }
 
   EDBM_update(me,