Make it possible to request a new runner token
It may happen that someone wants to revoke runner's token (when leaked screenshots with token for example).
Currently it is not possible to change runner token using a web interface. We have two options here:
- make it possible to revoke a runner's token using a web interface, runner will receive a new token next time it connects
- make it possible to request a new token using a CLI interface for gitlab-ci-multi-runner