LinkPickerDialog could expose onFolderSelected method for subclasses to use

Currently the LinkPickerDialog creates a NodePickerController which internally gets notified for when a user navigates in the folders at the left tree view of the picker dialog.

This issue is about exposing this notification on the LinkPickerDialog itself, so that subclasses can use the event. One of these subclasses is the Forge plugin Gallerypicker, see related forge issue HIPPLUG-866