Update Milestone Report page

Release notes

You can now view epics alongside issues and tasks in the Milestone Report, providing a complete picture of all work associated with your milestones. This enhancement builds on the ability to assign milestones to epics, creating a unified view that shows both strategic initiatives (epics) and tactical work (issues) in a single report.

Requirements

1. Replace the use of the "Issues" label across the report page ✅
   1. Update the "Display by" button labels to be Count and Weight ✅
   2. On the Count display mode:
      1. Update the left legend on the two charts to use Work items instead of Issues ✅
      2. On the Burnup chart, update the popover content to say [X] total [Y] completed (each on their own line like today)✅
   3. On the Weight display mode:
      1. On the Burndown chart, update the popover content to say [N] remaining weight ✅
      2. On the Burnup chart, update the popover content to say [X] total [Y] completed (each on their own line like today) ✅
   4. Update the "Issues" Tab (below the charts) to be Work items ✅
   5. Update the alert under the Issues Tab (present when over 500 items) to: Showing 500 of [N] items. View all ✅
   6. On the list headers (under the "Issues" Tab):
      1. Remove the term "Issues" from each of the lists ✅
      2. Move the description of the lists (ex: "open and unassigned") to a new line under the list heading, and use gl-font-sm and gl-text-subtle (small, gray text) ✅
      3. Use the work item icon instead of the issues icon (in progress – gitlab-svgs#438 (moved))
   7. On the sidebar of the report page:
      1. Update "Issues" (section under due date) to be Work items ✅
      2. Update "Total issue weight" to be Total weight ✅
2. Update report so that Epic work items are now being included in metrics / data. ✅
   1. Charts (burndown, burnup) ✅
   2. Sidebar "Issues" (now "Work items") count
   3. "Issues" (now "Work items") Tab and data ✅
      1. Count in the Tab should now include Epic work items. ✅
      2. Add the Type icon to items within the Lists, to differentiate work item types (see design) ✅
      3. List header should now include Epics in the count next to work item icon ✅

Designs

🎨 Please find the design proposal here.