Add Pipeline metrics worker
What does this MR do?
Creating a new Merge Request metrics is time consuming, because we need to access repository.
This makes this operation asynchronous, thus non-blocking for updating pipeline.
Are there points in the code the reviewer needs to double check?
Why was this MR needed?
Screenshots (if relevant)
Does this MR meet the acceptance criteria?
- CHANGELOG entry added
- Documentation created/updated
- API support added
- Added for this feature/bug
- All builds are passing
- Conform by the merge request performance guides
- Conform by the style guides
Branch has no merge conflicts with
master(if it does - rebase it please)
- Squashed related commits together