dev server: also proxy /data directory for testing replay from a remote instance locally (#266)

API_BASE_URL will need to be set to 'http://remote.example.com/' instead of 'http://remote.example.com/api/'

frontend/webpack.dev.js

@@ -43,9 +43,15 @@ module.exports = merge(common, {
         headers: {
           Host: devBackendUrl.host,
         },
-        pathRewrite: { "^/api": "" },
         ws: true,
       },
+
+      "/data": {
+        target: devBackendUrl.href,
+        headers: {
+          Host: devBackendUrl.host,
+        },
+      },
     },
     // Serve replay service worker file
     onBeforeSetupMiddleware: (server) => {