[FE] Add Lead Time and Cycle Time stage to group-level Value Stream Analytics

FE for #21863 (closed)

The following metrics should be added to group-level Value Stream Analytics:

• Lead Time, which should be measured as median time from issue creation to issue closed
• Cycle Time, which should be measure as median time from first commit to issue closed

NOTE: the titles should be left aligned

BE work is being implemented in !29791 (merged) (Please note: It is dependent on 3 other BE MRs being merged.)