Rename CanvasItem.update() to queue_redraw()

Affects a lot of classes. Very thoroughly checked signal connections and deferred calls to this method, add_do_method/add_undo_method calls, and so on.

Also renames the internal `_update_callback()` to `_redraw_callback()` for consistency.

Just a few comments have also been changed to say "redraw".

In CPUParticles2D, there was a private variable with the same name. It has been renamed to `do_redraw`.

editor/editor_properties_array_dict.cpp

@@ -509,7 +509,7 @@ void EditorPropertyArray::_notification(int p_what) {
 			if (is_visible_in_tree()) {
 				if (_is_drop_valid(get_viewport()->gui_get_drag_data())) {
 					dropping = true;
-					edit->update();
+					edit->queue_redraw();
 				}
 			}
 		} break;
@@ -517,7 +517,7 @@ void EditorPropertyArray::_notification(int p_what) {
 		case NOTIFICATION_DRAG_END: {
 			if (dropping) {
 				dropping = false;
-				edit->update();
+				edit->queue_redraw();
 			}
 		} break;
 	}