Posts, Post Types: Ensure that non-ASCII characters in attachment slugs aren't...

Posts, Post Types: Ensure that non-ASCII characters in attachment slugs aren't shown in urlencoded form in the sample permalink UI.

Fixes #35980

Built from https://develop.svn.wordpress.org/trunk@36853


git-svn-id: https://core.svn.wordpress.org/trunk@36820 1a063a9b-81f0-0310-95a4-ce76da25c4cd