Convert "reliable trigger" to TypeScript

ts/backbone/backboneJquery.ts

@@ -0,0 +1,6 @@
+// Copyright 2020-2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+// we are requiring backbone in preload.js, and we need to tell backbone where
+// jquery is after it's loaded.
+window.Backbone.$ = window.Backbone.$ || window.$;