Accessibility: Multiple controls on a single page creates issue

[kevinkidwell]

Description
Any element on a page must have a unique ID. This issue appears when items on a page both have the same ID, typically from embeds or other generated templates that can be repeated.

This particular issue is present on the Item Embed on the controls for an item: zoom in, zoom out, home, and fullscreen.

Solution
Remove IDs for zoom controls and replace with classes. Adjust any relevant code that referred to these IDs to refer to the classes instead. This will fix the accessibility issue when multiple Item Embeds are on the same page.

Related Issue
exhibits-library-cornell-edu#428