Value Streams Dashboard GA - adding dashboards list under group-level Analyze -> Dashboards

Problem to solve

GitLab Analytics provide high value to executives. However, these reports are spread across multiple pages in GitLab and may require specific filters to be applied to be relevant.

Proposal

Adding the "Dashboards list page" under group-level Analyze -> Dashboards.

Next iteration

Adding VSD comparison panel as visualization for the widget designer - will be done via #409949.