Media: Use '%d selected' for the selection string, and offer a comment to...

Media: Use '%d selected' for the selection string, and offer a comment to translators to help them find a workable solution with this would-be plural string. fixes #22749. see #22229.



git-svn-id: https://core.svn.wordpress.org/trunk@23075 1a063a9b-81f0-0310-95a4-ce76da25c4cd