Decouple plugins from instance-refreshed event

To be able to allow sidebar and databases-collections plugin to handle their data loading independently from each other and general instance refreshes and make the UI changes that will allow us to show databases and collections as soon as we have the minimun of the required info about them, we want to remove the dependency on instance-refreshed event as a way of communicating changes in instance model and instead make instance the main source of truth for this info and corresponding changes