LPS-27530 BookmarksEntry changes for new staging

Hey Julio,

This is the next batch for the bookmarks staging changes, more specifically changes for the BookmarksEntry entity.

The tactics for this PR is to have two commits one copying and pasting the logic into a new staged model data handler (not removing the original code) and applying the new logic.

By doing this the portal will still compile, the original logic is still preserved in the BookmarksPortletDataHandlerImpl. We will modify that as well of course, as soon as these get in.

Thanks,

Máté

cc: @KocsisDaniel