LPS-32847 Applying new staging architecture to DDLPortlet and DDLDisplay

Hey Julio,

These changes are implied by the compilation error in the DDL Form portlet. So the situation is that we cannot really solve it quickly if we do not roll back the changes, so before I fix the DDL Form portlet, I have to apply the new architecture to the DDL portlet as Brian asked, but unfortunately to the DDM portlet as well. After these I can fix the error in the DDL Form - which would be very easy once I complete these. I can ensure you this is the top priority for me.

So here goes the first step, applying the changes to DDL and DDL Display portlet. The next will be the DDM.

And one more thing, you might not noticed it, but I don't like the way we pass the elements to the different data handlers. We have a change for that coming in our queue anyway, we already started to figure out how could we nicely solve that.

Thanks,

Máté

cc: @KocsisDaniel