Create Harbor GraphQL type

The following discussion from !80999 (merged) should be addressed:

• @alexkalderimis started a discussion: (+4 comments)

  Should we add a GraphQL type as well? We can do this in a follow-up issue.

Implementation steps:

• add a GraphQL type under app/graphql/types/projects/services. An example to follow would be: JiraServiceType
• This type should expose all the fields that you want clients to be able to retrieve.
• This type should be added to the type resolver of ServiceType#resolve_type.

And you will want to add a test or two to spec/requests/api/graphql. An example is: https://gitlab.com/gitlab-org/gitlab/-/blob/master/spec/requests/api/graphql/project/jira_service_spec.rb