Media Grid: treat Edit Image like a `mode`, which it is, instead of a `state`, which it is not.

Fixes #29206.

Built from https://develop.svn.wordpress.org/trunk@29483


git-svn-id: http://core.svn.wordpress.org/trunk@29261 1a063a9b-81f0-0310-95a4-ce76da25c4cd