feat(editor): add page dragging area widget extension (#12045)

Closes: BS-3364

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

- **New Features**
  - Introduced a new "Page Dragging Area" widget, enabling enhanced block selection and drag area detection within the user interface.
  - Added utilities for more precise block selection based on rectangular selection areas.

- **Improvements**
  - Integrated the new widget into the view extension system for consistent behavior across supported views.
  - Enhanced clipboard handling with comprehensive adapter configurations for various data types.

- **Refactor**
  - Streamlined widget registration and block selection logic for improved maintainability and modularity.
  - Removed legacy widget exports and registrations to centralize widget management.

- **Chores**
  - Updated workspace and TypeScript configurations to support the new widget module.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/blocks/root/src/index.ts

@@ -16,7 +16,6 @@ export * from './preview/preview-root-block.js';
 export { RootService } from './root-service.js';
 export * from './types.js';
 export * from './utils/index.js';
-export * from './widgets/index.js';
 
 declare type _GLOBAL_ =
   | typeof PointerEffect