feat(editor): group gfx extension (#11950)

Closes: BS-3208

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- **New Features**
  - Introduced a new group view extension, enhancing how group elements are handled and displayed.
  - Added new store and view modules for group-related features, improving modularity and integration.

- **Refactor**
  - Updated the group element architecture to use extension-based registration for views, toolbars, and effects.
  - Simplified and reorganized exports for group and text modules.

- **Chores**
  - Updated dependencies and project references to improve build consistency and compatibility.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/gfx/group/src/group-watcher.ts

@@ -0,0 +1,36 @@
+import {
+  type SurfaceBlockModel,
+  SurfaceGroupLikeModel,
+  type SurfaceMiddleware,
+  surfaceMiddlewareExtension,
+} from '@blocksuite/affine-block-surface';
+
+const groupRelationWatcher: SurfaceMiddleware = (
+  surface: SurfaceBlockModel
+) => {
+  const disposables = [
+    surface.elementUpdated.subscribe(({ id, props, local }) => {
+      if (!local) return;
+
+      const element = surface.getElementById(id)!;
+
+      // remove the group if it has no children
+      if (
+        element instanceof SurfaceGroupLikeModel &&
+        props['childIds'] &&
+        element.childIds.length === 0
+      ) {
+        surface.deleteElement(id);
+      }
+    }),
+  ];
+
+  return () => {
+    disposables.forEach(d => d.unsubscribe());
+  };
+};
+
+export const groupRelationWatcherExtension = surfaceMiddlewareExtension(
+  'group-relation-watcher',
+  groupRelationWatcher
+);