Fix Lightbox use with Go theme and Carousel Gallery block

[AnthonyLedesma]

Description

The CoBlocks Lightbox works by adding click event listeners to document elements. Previous iterations of Lightbox worked by adding a click listener to the img elements which were arguably at the bottom of the document hierarchy. Because the event listener was near the bottom of hierarchy we made it possible for events to fire on elements that reside above our selected target. As a result of this bug, the Lightbox for Go theme when using the Carousel Gallery block would not function.

This PR changes the listener target from the lowest img element to the parent figure element of each respective image. This allows the event bubbling to function as expected even if theme styles result in click events firing on the Figure or the Img elements.

Screenshots

Types of changes

Minor JavaScript change to use .closest( 'figure' ) function.

How has this been tested?

Tested manually in Chrome, and Firefox.
Tested with and without the Gutenberg plugin active.
Tested with Go, TwentyTwenty, Barebones theme (underscores).

Checklist:

• My code is tested
• My code follows accessibility standards
• My code has proper inline documentation
• I've included any necessary tests
• I've included developer documentation
• I've added proper labels to this pull request