AEM Page Persistence Strategy: Use Page for configuration collection root resource

currently the Page Persistence Strategy uses cqage nodes for the collection items, but not for the collection root resource itself.

when a configuration collection is deleted, currently only the root resource gets deleted, bypassing the PageManager API. as a result the collection and the collection items are not deleted on the publish side.

we should use a cqage node for the collection root resource as well: when this collection root page gets deleted, the delete should be propagated to publish as well (including deleting the child pages for the collection item).

we also need to test if the delete is propagated correctly to publish if only one item of the collection is deleted, not the whole collection.