Adds status to stage

What does this MR do?

Adds the status field to StageType

Screenshots (strongly suggested)

query:

{
  project(fullPath: "root/wake-in-fright") {
    pipeline(sha: "ec3ced293880fa898a913662e9d055f3cc2d57c8"){
      status
    }
  }
}

response:

{
  "data": {
    "project": {
      "pipeline": {
        "status": "FAILED"
      }
    }
  }
}

Does this MR meet the acceptance criteria?

Conformity

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