Add pause and resume function for pipelines and jobs in web frontend
I'd be nice to able to pause and resume single CI jobs as well as all jobs of a pipeline together.
This is useful when one runs his_her own gitlab-runner
on not-too-strong hardware (laptop) which is also used to work on while jobs are running. Sometimes the load might be ok and the jobs can run while you work, sometimes you might want to have all resources for your work. I a set of jobs (e.g. the wxPython library Phoenix or Firefox) take up to 3 hours on different OS) you start to loose a lot of progress if you have to cancel all jobs when you're in need of resources.
I'm aware that one can pause and resume runners in the CI runners configuration.