Add shared dashboard listing to the group level
### Problem to solve
With https://gitlab.com/gitlab-org/gitlab/-/issues/388557+ projects will have a shared dashboard listing but it will not exist for groups.
### Final solution
We need to add the shared dashboard listing to the group-level.
### Implementation plan
~frontend / ~backend
**Behind the `group_analytics_dashboards` ~"feature flag"**
1. Create a new HAML file in `ee/app/views/groups/analytics` to add the Vue anchor point `#js-analytics-dashboards-list-app` copying the data from [`ee/app/views/projects/analytics/dashboards/index.html.haml`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/views/projects/analytics/dashboards/index.html.haml).
2. Update [`ee/app/assets/javascripts/analytics/analytics_dashboards/components/dashboards_list.vue`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/assets/javascripts/analytics/analytics_dashboards/components/dashboards_list.vue) to retrieve dashboards from the group-level rather than project-level.
* _TODO: Figure out more detailed steps and ~backend changes_
3. Update unit tests at [`ee/spec/frontend/analytics/dashboards`](https://gitlab.com/gitlab-org/gitlab/tree/b26d9153d8e3d85dae9b2e76b241a14cb65d502c/ee/spec/frontend/analytics/dashboards).
4. Moved to #417771 ~~Copy feature spec from [`ee/spec/features/projects/analytics/dashboards_spec.rb`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/spec/features/projects/analytics/dashboards_spec.rb) and put it at `ee/spec/features/groups/analytics/dashboards_spec.rb` and update to check the group-level dashboard~~
* ~~_Opportunity to DRY this and move shared logic to shared examples_~~
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