Add missing routes to make group edits work

6b90ccb9 changed the routes so that users/groups can be accessed via/:id, but the Rails form_for method expects to use the groups#show path helper for the form action URL. This causes group edits and deletes to fail because the PUT/PATCH/DELETE methods did not exist for /:id. This MR adds these methods so that form_for continues to work.

Closes #23306 (closed)