Add a pipeline visualization for jobs

Right now it's difficult to tell why pipelines take so long when the longest job is not nearly as long. For example, in https://gitlab.com/gitlab-org/gitlab-ee/pipelines/9061665/builds, the pipeline took 3 hours when the longest job is 90 minutes. It would really help to have a timeline visualization, sort of like Chrome's Network browser:

/cc: @bikebilly