Move the visual positioning of the posts search form into it's DOM position. Fixes an accessibility bug where the keyboard focus sequence did not match the visual order. Change the media search form in list view to match the format of other post views. Give search forms a consistent layout on mobile.
Props oglekler, sabernhardt, joedolson.
Fixes#57949.
Built from https://develop.svn.wordpress.org/trunk@56023
git-svn-id: http://core.svn.wordpress.org/trunk@55535 1a063a9b-81f0-0310-95a4-ce76da25c4cd
