Use webpack worker-loader to load the IndexedDB worker instead of homegrown hack

src/@types/worker-loader.d.ts

@@ -0,0 +1,23 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+declare module "*.worker.ts" {
+    class WebpackWorker extends Worker {
+        constructor();
+    }
+
+    export default WebpackWorker;
+}