Add team metrics dashboard for Plan:Project Management BE

This is based off !32613 (merged) / https://clemmakesapps-master-patch-29126.about.gitlab-review.app/handbook/engineering/management/index.html#custom-team-metrics-dashboard.

@acroitor @digitalmoksha @egrieff @engwan @mdelaossa @pderichs FYI. It is possible to filter by an individual person (or people), but that's not the point of this dashboard, I'm mostly interested in the team overall.

cc @johnhope @donaldcook if you want to do this for your teams.