CORE-4182 Fix for AppWizardDiskResourceSelector::setValue.

Updated AppWizardDiskResourceSelector::setValue to set the given value to selectedResource, which is now a HasId type.
Removed unused getSelectedResource method.
Fix for AppWizardDiskResourceSelector browse click.

Removed the onBrowserEvent override, since this made the File/Folder selection dialog open twice when the browse button was clicked.