[ENG] Show more info on hover of trial status in sidebar

Child of #220930 (closed).

• Use hover interaction to display a popover with more information in it
  • Close popover when the user hovers out of the bounds of the widget and/or popover
• Include buttons to [Upgrade {group name} to Ultimate] & [Compare plans]
• Track which namespaces on in the control vs. experimental cohorts
• Track the view rate of the popover by the experiment group
• Track the view-to-click rate by the experiment group
• Report on the average and median number of views per user or namespace for the experiment group
• Track the trial upgrade rate of the control vs. experimental cohorts
  • Use the ExperimentSubject’s converted_at column as a shortcut to this data

Additional Notes

• As we’re in the midst of EoA for Gold, Silver, & Bronze plans, we’ll also need to pivot the language in the widget & popover to match the new plans: Premium & Ultimate.
• It could be interesting to A/B test the whole sidebar item being clickable as the expected action to take and the sidebar item not being clickable but hover-able to show a popover which then has buttons of actions to take