refactor: moving connector label to connector view (#11738)

### Changed
Moved connector label moving logic from `default-tool` to connector view.

#### Other infrastructure changes:​​
- Gfx element view now can handles drag events
- Added `context.preventDefault()` support to bypass built-in interactions in extension
- Handle the pointer events in element view will bypass the built-in interactions automatically

> The built-in interactions include element dragging, click selection, drag-to-scale operations, etc.

blocksuite/framework/std/src/gfx/index.ts

@@ -24,6 +24,7 @@ export type {
   ExtensionDragEndContext,
   ExtensionDragMoveContext,
   ExtensionDragStartContext,
+  GfxInteractivityContext,
   SelectedContext,
 } from './interactivity/index.js';
 export {