Feat/startup config api (#518)

* feat: add api for config

* feat: add data service to client

* feat: update client pages with values from config endpoint

* test: update tests

* Update configurations and documentation to remove VITE_SHOW_GOOGLE_LOGIN_OPTION and change VITE_APP_TITLE to APP_TITLE

* include APP_TITLE with startup config

* Add test for new route

* update backend-review pipeline

* comment out test until we can figure out testing routes in CI

* update: .env.example

---------

Co-authored-by: fuegovic <32828263+fuegovic@users.noreply.github.com>

api/server/routes/config.js

@@ -0,0 +1,18 @@
+const express = require('express');
+const router = express.Router();
+
+router.get('/', async function (req, res) {
+  try {
+    const appTitle = process.env.APP_TITLE || 'LibreChat';
+    const googleLoginEnabled = !!process.env.GOOGLE_CLIENT_ID && !!process.env.GOOGLE_CLIENT_SECRET;
+    const serverDomain = process.env.DOMAIN_SERVER || 'http://localhost:3080';
+    const registrationEnabled = process.env.ALLOW_REGISTRATION || true;
+    
+    return res.status(200).send({appTitle, googleLoginEnabled, serverDomain, registrationEnabled});
+  } catch (err) {
+    console.error(err);
+    return res.status(500).send({error: err.message});
+  }
+});
+
+module.exports = router;