GraphQL PMG - job action mutations

What does this MR do and why?

Part 2 of 3 for #467279 (closed)

• Part 1 - Render job action buttons
• Part 2 - Job action mutations < you are here
• Part 3 - Confirmation modal

This MR wires in the job action mutations. When you click an action button, the necessary mutation will fire and the job status will update.

How to set up and validate locally

Prerequisites

• An enabled feature flag: Feature.enable(:ci_graphql_pipeline_mini_graph)
• A working runner

Steps

1. Navigate to a project (this example uses the flightjs group)
2. Navigate to the Pipeline Editor (Build > Pipeline editor)
3. Trigger a pipeline
4. Once the pipeline appears in the pipeline editor widget, click on a stage
5. You should see the dropdown with a list of jobs and action buttons
6. Click an action button to test out the mutations.

Example gitlab-ci.yml if you'd like to see different job types

job: 
  script:
    - sleep 5
  when: delayed
  start_in: 2 minutes

another_job:
  script:
    - sleep 5
  when: manual

another_job_2:
  script:
    - sleep 15
  when: on_failure