Acq: Highlight number received when less than invoiced

Somewhat similar to bug 1270015.

On invoices, it would be helpful if the count of items received was highlighted (or changed to something like red font) when the number received is less than the number being billed.

This would provide an easy visual cue to libraries that there's an issue with what they've been billed for vs what they've received. Right now it's tedious to go through each line item to check the numbers.

That should be an innocuous enough change that libraries who aren't concerned with matching those numbers to ignore, and libraries who are concerned about it to be adequately flagged that there's something of note.