Remove remaining JSON requires (#20110)

* Remove remaining JSON requires

* Lint

* Update feature-flags.js

lib/read-json-file.js

@@ -0,0 +1,14 @@
+const fs = require('fs')
+const path = require('path')
+
+module.exports = function readJsonFile (xpath) {
+  return JSON.parse(
+    fs.readFileSync(
+      path.join(
+        process.cwd(),
+        xpath
+      ),
+      'utf8'
+    )
+  )
+}