Enable more react pages (#19935)

* enable more react landing pages

* move nextjs page logic to separate middleware

* enable codespaces landing page + fixes

* enable /education

* enable /admin

* use pathToRegexp to match routes for react rendering

* run lint

* fix: typo in url

* update sidebar test

middleware/is-next-request.js

@@ -0,0 +1,52 @@
+const pathToRegexp = require('path-to-regexp')
+
+const { FEATURE_NEXTJS } = process.env;
+
+const productIds = [
+  // 'actions',
+  'admin',
+  "billing",
+  "code-security",
+  "codespaces",
+  "communities",
+  "desktop",
+  "developers",
+  "discussions",
+  // 'early-access',
+  "education",
+  // 'github',
+  "graphql",
+  // 'insights',
+  "issues",
+  "organizations",
+  // 'packages',
+  "pages",
+  "rest",
+  "sponsors",
+];
+
+const landingPageExp = pathToRegexp('/:locale/:versionId?/:productId')
+
+module.exports = function isNextRequest(req, res, next) {
+  req.renderWithNextjs = false;
+
+  if (FEATURE_NEXTJS) {
+    if ('nextjs' in req.query) {
+      req.renderWithNextjs = true;
+    } else {
+      // Custom path matching to determine if we should render with nextjs
+
+      // Remove any query string (?...) and/or fragment identifier (#...)
+      const { pathname } = new URL(req.originalUrl, "https://docs.github.com");
+
+      // Should the current path be rendered by NextJS?
+      const landingPageMatch = landingPageExp.exec(pathname)
+      if (landingPageMatch) {
+        const productId = landingPageMatch[3]
+        req.renderWithNextjs = productIds.includes(productId)
+      }
+    }
+  }
+
+  next();
+};