GraphQL API: Jobs of a runner

Background

Related to #347856 (closed), jobs tab: #347856[View_specific_runner_-_jobs.png]

The new view-only page #347856 (closed) displays a list of jobs that a runner has run (or is running).

Description

So we must provide a list of jobs a given runner as well as the project this job belongs to.

query getRunners{
  runners{
    nodes {
      id
      description
      jobs { # NEW field on CiRunner!
        nodes{
          status
          id
          tags
          finishedAt
          shortSha
          commitPath
        }        
      }
    }
  }
}

Implementation notes:

The first iteration of this tab requires us to show the 30 more Recent jobs, so having this SORT could be considered to have the list of jobs.