LPS-34639 Display numbers in publish to live

Hey Julio,

I send you the PR for the display of the number of publishable items in the Publish to Live form. I removed the unthrown exceptions in PublishLayoutsAction and EditLayoutsAction, and made the first extend the second to reuse the permission checking logic, as in EditLayoutSetAction.

I also found an error with the date property in the dynamic query in DeleteSystemEventExporter. A Date object must be used instead of a long object. I've fixed but I cc @mhan810 so he validates it.

Thanks

@LeventeHudak