Add achievements UI

What does this MR do and why?

Add a basic UI to show group achievements.

Screenshots or screen recordings

Screen_Recording_2024-02-06_at_20.35.49

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Enable the achievements feature flag in the rails console: Feature.enable(:achievements)
2. Navigate to a group achievements page (no navigation menu item exists at the moment): http://gdk.local:3000/groups/twitter/-/achievements
3. If there there no achievements for the group you should see the message saying such.
4. Create some achievements (in the rails console): FactoryBot.create_list(:achievement, 25, namespace: Group.find(33))
5. Check the group achievements page again- you should see the achievements and be able to page back/forth.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #410003 (closed)