Organization level user dashboard page

In the pods blueprint we describe how we will eventually need to phase out global pages like /dashboard and instead redirect users to "organization specific pages" like /organizations/bigcompany/dashboard.

This issue is to build a user dashboard page for the organization level.

MVC designs are available at #390205 (closed)

This work should sit behind a generic feature flag that will hide multiple organization dashboard pages.

We need to update the link in app/assets/javascripts/organizations/show/components/association_counts.vue#L60 to point to the users page.

Designs

Implementation plan

See tasks for this issue