Add logic for fetching pipeline creation status

What does this MR do and why?

Add some logic for fetching pipeline creation status.

• Add a Ci::PipelineCreation type with status and pipeline_id
• Add a PipelineCreationMetadata model to store logic for storing and fetching pipeline creation data

Co-Authored By: Avielle Wolfe awolfe@gitlab.com

#479815 (closed)

MR acceptance checklist

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Screenshots or screen recordings

{
  project(fullPath:"gitlab-org/test-project") {
    id
    ciPipelineCreation(id: "123") {
      status
      pipelineId
    }
  }
}

{
  "data": {
    "project": {
      "id": "gid://gitlab/Project/21",
      "ciPipelineCreation": {
        "status": "CREATING",
        "pipelineId": null
      }
    }
  }
}

How to set up and validate locally

1. In the console:

   Rails.cache.write(format(Ci::PipelineCreationMetadata::REDIS_CACHE_KEY, project_full_path: project.full_path, pipeline_creation_id: '123'), { status: :creating, id: nil})

2. Run query as above, see the status returned.

NOTE: This will not return a pipelineId yet. That logic is yet to be implemented.

Related to #479811