dashboard: predefined system roles don't include read access to grafana scope
The current predefined system roles (like block-manager, cluster-manager, pool-manager, etc..) don't include read access to grafana scope and thus prevent a user without the administrator role to see the grafana dashboards.
For instance, a user that just has the "pool-manager" role will not be able to see the grafana tab in the dashboard UI.
The current workaround is to create a custom role with the grafana scope read access enabled and add that custom role to the non-admin user.
We should include the read access to the grafana scope in all predefined "*-manager" system roles.