feat: Convert helpers to use JS files

packages/backend/src/helpers/app-assets-handler.js

@@ -0,0 +1,20 @@
+import express from 'express';
+
+const appAssetsHandler = async (app) => {
+  app.use('/apps/:appKey/assets/favicon.svg', (req, res, next) => {
+    const { appKey } = req.params;
+    const svgPath = `${__dirname}/../apps/${appKey}/assets/favicon.svg`;
+    const staticFileHandlerOptions = {
+      /**
+       * Disabling fallthrough is important to respond with HTTP 404.
+       * Otherwise, web app might be served.
+       */
+      fallthrough: false,
+    };
+    const staticFileHandler = express.static(svgPath, staticFileHandlerOptions);
+
+    return staticFileHandler(req, res, next);
+  });
+};
+
+export default appAssetsHandler;