[6.x] Hide the expand layout control when the content is small and it has no effect

[JayGeorge]

Description of the Problem

Sometimes the new expand layout control button in the header doesn't appear to do anything because the content wrapper is already narrower than the available width, so it has no effect on the current page.

For example, on the Create screens, the button doesn't appear to do anything

What this PR Does

• Tests for a smaller inner wrapper using a CSS selector and hides the button if a smaller wrapper is present

How to Reproduce

1. Go to page with a smaller width such as create collection, a dashboard with no widgets, utilities index, cache manager, search utility, configure sites, user groups index, permissions index, and try to press the expand layout width button
2. After this commit you won't see the button on those pages

[jackmcdade]

Smart!