Get list view button working more consistently

[johngodley]

The list view button is provided by Gutenberg and it has some internal dynamic list view system that adjusts what is shown in the list depending on the viewport. This makes assumptions that the editor is full screen, and as such it works in an inconsistent way here. The underlying problem seems to be that Gutenberg is looking for a scrollable container. If the Blocks Everywhere editor is small then it doesn't find one, but as it gets a bit bigger then it does.

Fixing this may require changes to Gutenberg.