Settings driver should not directly release the shell settings

[MikeAlhayek]

Currently when a core site settings change, we reload the shell settings directly in the driver. If we have multiple drivers contributing to the same settings group, we run into issue of releasing the shell multiple times or releasing it when unnecessary.

We should have a way for the settings driver to request the tenant to be reloaded. In the controller, we then reload the settings only when we have a request and the settings has been validated.

This should reduce the cost of unnecessary tenant reloading.