Media Library should scope its styles

Problem/Motivation

So Experience Builder managed to integrate Media Library into its UI. How they went about it is both epic and extremely clever.

XB has a mechanism to automatically scope Media Library's styles, but it would help the cause, quite a bit, if Media Library took the effort to "fence"/scope-control its styles to begin with. We could use the @scope directive, and whatever other clever CSS things we need to accomplish this goal. The main benefit here is that it would be a strong example for other "unique" UIs in the Drupal system of how to integrate cleanly with Experience Builder.