[hub] [gql] prompt versions list

[mikeldking]

For a given prompt, we want to be able to pull prompt versions. E.g.

This ticket is to wire up a node based API for the version history from the database.

query {
   prompt: node(id: asdfasdf) {
      name
      versions {
        edges {
            template_version: node {
                  user
                  description
                  template
                  tools
            }
        }
      }
   }
}

query node {
    templateVersion: node($nodeId) {
          id
         ... on PromptVersion {
              user
              description
              template
              tools
         }
    }
}