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/widgets/page-dragging-area/src/effects.ts

@@ -0,0 +1,11 @@
+import {
+  AFFINE_PAGE_DRAGGING_AREA_WIDGET,
+  AffinePageDraggingAreaWidget,
+} from './index';
+
+export function effects() {
+  customElements.define(
+    AFFINE_PAGE_DRAGGING_AREA_WIDGET,
+    AffinePageDraggingAreaWidget
+  );
+}