Init Danger/Endanger with Backbone/package.json versions rules

dangerfile.js

@@ -0,0 +1,8 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+// Ensuring that the root directory is the same as this file before we load any
+// danger code. This is needed so we can run danger with the danger/package.json
+// file in CI
+process.chdir(__dirname);
+require('./danger/rules.ts');