MCE view controls:

* Move controls back over to the left, as they were before. Wide images and muscle memory have been causing frustration.
* Improve the experience and unify the UI of media view controls. Audio and video views now require an initial click to select before further interaction.
* CSS clean up and organization.

fixes #27320, #27542.

Built from https://develop.svn.wordpress.org/trunk@27777


git-svn-id: http://core.svn.wordpress.org/trunk@27614 1a063a9b-81f0-0310-95a4-ce76da25c4cd