LPS-37542 All portlets must have a portlet data handler, even if they don't explicitly handle configuration

Any portlet may have at least look and feels preferences, even if it does not have a ConfigurationAction class.
LPS-37542 Remove unnecessary portletDataHandler null checkings
LPS-37542 Do not exclude portlets without ConfigurationAction from the export, import and publish application lists
LPS-37542 Lang keys