Replace "Advanced Search" button with icon on small screens

[Steve-A-Orr]

I've recently had a library employee point out that on small mobile device screens, the search icon (magnifying glass) and Advanced Search button get mashed together. (This makes it somewhat successful in being responsive, but not optimal.) I was then shown that the new Primo UI itself handles this situation by replacing that button with a "primo-ui:tune" icon.

So, I propose we configure onesearch-local to do the same--maybe through a media query or built-in Angular function. I don't know the solution, I'm just in the "propose and idea" phase. I'll look into it and report back if I find an acceptable approach.