Exec Dashboards PoC: Add flow metrics to the "Metrics comparative table"

Overview

Once Exec Dashboards PoC: Separate comparative table... (#378373 - closed) is completed, we need to add to the PoC the additional key metrics (aka [flow metrics) for the MVC.

Problem to solve

Proposal

1. Add the value stream key metrics to the comparative table:

   1. Lead time: Median time from when the issue was created to when it was closed.

   2. Cycle time: Median time from first commit to issue closed.

   3. New issues: Number of new issues created.

   4. Deploys: Total number of deployments to production.

      *VSA filters are out-of-scope.

2. Pre-selecting the sub-groups / projects to be displayed will be done by passing in URL parameters.

Acceptance criteria

Compare Flow and DORA metrics between these projects in one view:

1. GitLab.org / GitLab FOSS
2. GitLab.org / GitLab
3. GitLab.org / GitLab Design
4. GitLab.org / GitLab Docs