Expose userAchievements count via GraphQL

What does this MR do and why?

Expose userAchievements count via GraphQL

Changelog: added

Screenshots or screen recordings

How to set up and validate locally

Hopefully your db is already seeded with some achievements

Run the following from http://gdk.test:3000/-/graphql-explorer

query {
  currentUser {
    userAchievements {
      count
      nodes {
        achievement {
          name
          userAchievements {
            count
          }
        }
      }
    }
  }
}

MR acceptance checklist

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