fix: export the layer constants. (#8256)

* fix: export the layer constants.

* refactor: remove @internal annotations from layer constants.

core/blockly.ts

@@ -161,6 +161,7 @@ import {Marker} from './keyboard_nav/marker.js';
 import {TabNavigateCursor} from './keyboard_nav/tab_navigate_cursor.js';
 import {MarkerManager} from './marker_manager.js';
 import type {LayerManager} from './layer_manager.js';
+import * as layers from './layers.js';
 import {Menu} from './menu.js';
 import {MenuItem} from './menuitem.js';
 import {MetricsManager} from './metrics_manager.js';
@@ -585,3 +586,4 @@ export {ZoomControls};
 export {config};
 export {inject};
 export {serialization};
+export {layers};

core/layers.ts

@@ -7,13 +7,11 @@
 /**
  * The layer to place blocks on.
  *
- * @internal
  */
 export const BLOCK = 50;
 
 /**
  * The layer to place bubbles on.
  *
- * @internal
  */
 export const BUBBLE = 100;