feat(editor): connector gfx extension (#11940)

Closes: BS-3207

blocksuite/affine/blocks/surface/src/managers/connector-manager.ts

@@ -850,6 +850,7 @@ function renderRect(
   ctx.restore();
 }
 
+// TODO(@mirone): move to connector package
 export class ConnectionOverlay extends Overlay {
   static override overlayName = 'connection';