Improve `Workers` page

[Liam-DeVoe]

followup to #149

• default slider range to the "current campaign", quantified as "the latest time interval where at least one worker is running for the entire interval".
  • add a calendar selector for setting an arbitrary slider range
  • and a button for going back to "current campaign", as well as "last day", "last week", "last month"
• show more information from WorkerIdentity in the worker details? Unclear what information is most valuable
• search/filter box for worker identities? (what fields though?)
• don't update when dragging slider, and don't reset slider on update
• some way to reset the slider to the full range (maybe click on the current range button?)
• inverse view, where nodeids are the rows and we show active workers for those targets?
  • in this view, workers can overlap on the same target, making the ui harder