LPS-42517 Add portlet data handler skeleton for assets and register it
LPS-42517 No logic changes - move code to new PortletDataHandler
LPS-42517 Apply changes to the new portlet data handler
LPS-42517 Apply changes to the staging framework to accomodiate the new PDH
LPS-42517 Removing old methods from the interal API
LPS-42517 Update test classes to accomodiate changes