feat(delete): add delete method to createDataProvider

related: #11

packages/ra-cubicweb/src/createDataProvider.ts

 import { client } from "@logilab/cwclientlibjs";
-import { AuthProvider, DataProvider } from "ra-core";
+import { AuthProvider, DataProvider, DeleteResult } from "ra-core";
 import { Schema } from "./Schema";
 import { deduplicate } from "./utils/deduplicate";
 
@@ -245,8 +245,13 @@
     return Promise.resolve({ data: { ...data, id: eid } });
   };
 
-  const _delete: DataProvider["delete"] = (_resource, _params) =>
-    Promise.reject("Not implemented");
+  const _delete: DataProvider["delete"] = async (resource, data) => {
+    await rqlClient.queryRows(`
+      DELETE ${resource} X WHERE X eid ${data.id}
+    `);
+    // FIXME: find how to correctly specify type without "any"
+    return { data: data.previousData } as DeleteResult<any>;
+  };
 
   const deleteMany: DataProvider["deleteMany"] = (_resource, _params) =>
     Promise.reject("Not implemented");