Real-time CI status updates for last commit

What?

Build real-time CI status updates for a projects home view.

Where?

A projects home view https://gitlab.com/gitlab-org/gitlab CI status

Technical Proposal

1. Create a feature flag real_time_ci_status
2. Create a new component to house ci_icon.vue (maybe real_time_ci_status.vue)
3. The component should use GraphQL subscriptions to pull real-time status updates (subscription TBD)
4. Inject the new feature flag into app/assets/javascripts/repository/components/last_commit.vue to display the real-time CI status component based on flag state (true) or the old ci_icon.vue component (false).
5. Write good test coverage!!!