Add alt-tag fields to slide content component

[cwbragg]

Is your feature request related to new functionality not yet included in the product? Please describe.
New

Is your feature request related to a problem or a change to existing functionality? Please describe.
Problem. Images in sliders do not have an alt-tag field

Describe the solution you'd like
Alt-tag field within the slide content component

Describe alternatives you've considered
Alt-tags added to images in the media library do not appear on pages that images are added to.

This would be an even better solution - one place to add alt-tags that carry over to pages that images are in.

How will this impact users?
Staff can easier add alt-tags.
Patrons with disabilities can use screen readers to learn more about the content.

Additional context
Add any other context or screenshots about the feature request here.