[TECH SUPPORT] LPS-46235 Web Content Display Portlet doesn't import referenced File

Hi Dani,

I have built my changes based on LPS-46232. Unfortunately I could not test the LayoutImporter part because the portlet throws NPE even without my changes when a layout is imported.

Also, please note that this fix does not cover use cases for scope groups (which would matter in JournalContentPDH) so the behavior will be as-is for scope groups.

Please review my changes.

Thanks,
Ákos