feat(deleteMany): implement deleteMany of createDataProvider.

related: #11

packages/ra-cubicweb/src/createDataProvider.ts

@@ -253,8 +253,12 @@
     return { data: data.previousData } as DeleteResult<any>;
   };
 
-  const deleteMany: DataProvider["deleteMany"] = (_resource, _params) =>
-    Promise.reject("Not implemented");
+  const deleteMany: DataProvider["deleteMany"] = async (resource, data) => {
+    await rqlClient.queryRows(`
+      DELETE ${resource} X WHERE X eid IN (${data.ids.join(", ")})
+    `);
+    return { data: data.ids };
+  };
 
   return {
     getList,