Media: Fix vertical and horizontal alignment of the gallery "Random" checkbox,...

Media: Fix vertical and horizontal alignment of the gallery "Random" checkbox, and checkbox settings in general. Includes RTL. props koopersmith. fixes #22724.



git-svn-id: https://core.svn.wordpress.org/trunk@23034 1a063a9b-81f0-0310-95a4-ce76da25c4cd