feat: edgeless dnd (#9988)

### Changed
- Support edgelss dnd
- Simplify the drag-handle state

blocksuite/affine/widget-drag-handle/src/middleware/blocks-filter.ts

@@ -0,0 +1,49 @@
+import type { SurfaceBlockModel } from '@blocksuite/affine-block-surface';
+import type { BlockStdScope } from '@blocksuite/block-std';
+import { isGfxGroupCompatibleModel } from '@blocksuite/block-std/gfx';
+import type { TransformerMiddleware } from '@blocksuite/store';
+
+/**
+ * Used to filter out gfx elements that are not selected
+ * @param ids
+ * @param std
+ * @returns
+ */
+export const gfxBlocksFilter = (
+  ids: string[],
+  std: BlockStdScope
+): TransformerMiddleware => {
+  const selectedIds = new Set<string>();
+  const store = std.store;
+  const surface = store.getBlocksByFlavour('affine:surface')[0]
+    .model as SurfaceBlockModel;
+  const idsToCheck = ids.slice();
+
+  for (const id of idsToCheck) {
+    const blockOrElem = store.getBlock(id)?.model ?? surface.getElementById(id);
+
+    if (!blockOrElem) continue;
+
+    if (isGfxGroupCompatibleModel(blockOrElem)) {
+      idsToCheck.push(...blockOrElem.childIds);
+    }
+
+    selectedIds.add(id);
+  }
+
+  return ({ slots, transformerConfigs }) => {
+    slots.beforeExport.on(payload => {
+      if (payload.type !== 'block') {
+        return;
+      }
+
+      if (payload.model.flavour === 'affine:surface') {
+        transformerConfigs.set('selectedElements', selectedIds);
+        payload.model.children = payload.model.children.filter(model =>
+          selectedIds.has(model.id)
+        );
+        return;
+      }
+    });
+  };
+};