Add error_messages to GraphQL

What does this MR do and why?

Add error_messages to GraphQL. This will allow us to start moving away from yaml_errors and using ci_pipeline_messages in order to be able to eventually drop the yaml_errors field.

Changelog: added

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• #507284 (closed)

How to set up and validate locally

Trigger an error laden pipeline. In the graphql-explorer, run the following query:

{
  project(fullPath: "gitlab-org/test-project") {
    pipelines {
      nodes {
        errorMessages {
          content
        }
      }
    }
  }
}

Errors appear:

{
  "data": {
    "project": {
      "pipelines": {
        "nodes": [
          {
            "errorMessages": [
              {
                "id": "gid://gitlab/Ci::PipelineMessage/139",
                "content": "jobs:trigger_job config contains unknown keys: description"
              }
            ]
          },
          {
            "errorMessages": [
              {
                "id": "gid://gitlab/Ci::PipelineMessage/138",
                "content": "jobs:trigger_job config contains unknown keys: description"
              }
            ]
          },
          {
            "errorMessages": [
              {
                "id": "gid://gitlab/Ci::PipelineMessage/137",
                "content": "jobs:trigger_job config contains unknown keys: description"
              }
            ]
          },
          {
            "errorMessages": [
              {
                "id": "gid://gitlab/Ci::PipelineMessage/136",
                "content": "jobs:trigger_job config contains unknown keys: description"
              }
            ]
          },
          {
            "errorMessages": [
              {
                "id": "gid://gitlab/Ci::PipelineMessage/135",
                "content": "jobs:trigger_job config contains unknown keys: description"
              }
            ]
          },