Add CREATED_AT and UPDATED_AT as GraphQL group query sort options

What does this MR do and why?

Needed for &13790 (closed)

We want to be able to sort GraphQL group queries by created_at and updated_at but those options aren't in the enum. This MR adds those to the enum.

How to set up and validate locally

1. Go to /-/graphql-explorer
2. Run the following query

query {
  currentUser {
    groups(sort: CREATED_AT_DESC) {
      nodes {
        createdAt
      }
    }
  }
}

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