refactor(editor): move connector overlay to connector package (#11944)

blocksuite/affine/blocks/surface/src/extensions/surface-middleware.ts

@@ -0,0 +1,23 @@
+import { createIdentifier } from '@blocksuite/global/di';
+import type { ExtensionType } from '@blocksuite/store';
+
+import type { SurfaceBlockModel } from '../surface-model';
+
+export type SurfaceMiddleware = (surface: SurfaceBlockModel) => () => void;
+
+export const surfaceMiddlewareIdentifier = createIdentifier<{
+  middleware: SurfaceMiddleware;
+}>('surface-middleware');
+
+export function surfaceMiddlewareExtension(
+  id: string,
+  middleware: SurfaceMiddleware
+): ExtensionType {
+  return {
+    setup: di => {
+      di.addImpl(surfaceMiddlewareIdentifier(id), {
+        middleware,
+      });
+    },
+  };
+}