The popup to invite friends to communities has so far always been a brand new
popup that's opened on top of possible existing popups.
The design however, expects that the same section should be shown as part
of a wizard-like process inside of the existing community profile overview
popup, when entered from there.
This commit extracts the invite friends popup section into component that
can be reused as stack view, as well as modal content, to implement both
scenarios.
Pascal Precht