Description

We want to show the name of the current theme in the prompt text when users are to activate a previewing theme.

HEs get questions from users about this, like "I want to go back to the previous theme", so resolving this issue might help mitigate that. pdtkmj-1JP-p2#comment-3193

Project Thread: pbxlJb-3Uv-p2

Related

I had a try in WordPress/gutenberg#54587, but getCurrentTheme does not make sense since theme-previews.php overrides get_stylesheet() anyway.