Refactor and add generators for keystatic and package

The changes include refactoring the create-reader in cms keystatic and changing @keystatic/next version. Additionally, code generators for keystatic and package have been added, and corresponding templates have been organized into their respective directories.

turbo/generators/templates/keystatic/page.tsx.hbs

@@ -0,0 +1,5 @@
+// src/app/keystatic/[[...params]]/page.tsx
+
+export default function Page() {
+  return null;
+}