NXP-12896: Fix page size selector management on content views (adapted for 5.6.0 where content view templates organization have changed)

Conflicts:

	nuxeo-platform-contentview-jsf/src/main/java/org/nuxeo/ecm/platform/contentview/jsf/ContentViewImpl.java
	nuxeo-platform-contentview-jsf/src/main/java/org/nuxeo/ecm/platform/contentview/seam/ContentViewActions.java
	nuxeo-platform-webapp-base/src/main/resources/web/nuxeo.war/incl/content_view_page_size_selector.xhtml