mgr/dashboard: Suggest enabling newly supported features
The dashboard should recommend enabling features/functions that the Ceph community deems generally beneficial, but that not have been previously enabled by default. The user should get the choice of performing the particular change now, being reminded later, or never again. (As in other systems.)
One such example would be the pg_autoscaler. This was not always supported, and enabling it will have some impact on the system (so we can't enable it automatically always on upgrade). Yet, once a cluster is uptodate enough (all daemons >= 14.2.2, say), we should push a recommendation to the user.