LPS-33626 Use new context based root element for portlet-data.xml in BasePortletDataHandler
LPS-33626 Cleaning up doExportData and doImportData methods
LPS-33626 Apply portlet-data.xml null check in PortletImporter so PortletDataHandlers don't have to
LPS-33626 Apply changes - new pattern to JournalContentPortletDataHandler as example
LPS-33626 Apply same pattern to all portlet data handlers
LPS-33626 Fixing PageRatingsPortletDataHandler to produce a proper xml file otherwise it won't be possible to import