web frontend: centralize job listings in a single template

We currently have several places where we list jobs, and each one is copy/pasting the same template code. We should instead have a single template for presenting a list of jobs, and have that reused across all those places. The one in the test history page (lib/debci/html/templates/history.erb) is the most complete one, so it should be used as a base. Things to consider:

• the list of jobs itself must be passed as a parameter (locals: {...})
• some pages need to display logs/artifacts etc, others don't; this needs to be a parameter
• some pages need to display the test status, but others don't (e.g. listings of pending jobs); this needs to be a parameter as well.