SPIKE: include Lighthouse Accessibility test in CI

[mark-dce]

STORY As a repository owner, I'm concerned that my site's accessibility doesn't degrade with new features, so I would like to be able to monitor accessibility statistics and have the system alert me if they show any decline as new code is added to the project.

Main lighthouse site https://developers.google.com/web/tools/lighthouse

See #314 for more details about lighthouse.

ACCEPTANCE

• [x] Research if any mechanism exists to add lighthouse tool or similar testing tool to CI runs
• [x] Implement a proof of concept (if simple) or write a ticket and scope the effort to add this functionality (if more complex)
• [x] [OPTIONAL] use any remaining time to research other strategies to automate accessibility testing

[DraxIndustries79]

Note: Rob Kaufman mentioned he may know some tools to do this

[FCRodriguez7]

Resources for understanding this work

https://github.com/dequelabs/axe-matchers

https://github.com/accesslint/accesslint-ci

https://thoughtbot.com/blog/introducing-accesslint-web-accessibility-testing-in-ci

https://www.peterkrantz.com/2006/accessibility-in-rails-with-raakt/

https://developers.google.com/web/tools/lighthouse

[FCRodriguez7]

I also ran axe an accessibility tool used by Yale. The results for axe are here. There's a [ruby gem for axe] (https://github.com/dequelabs/axe-matchers). And an article on how to implement the axe gem.

[FCRodriguez7]

I added the appropriate gems and code to generate RSpec accessibility testing for demoing a part of the code with accessibility errors.

PR: https://github.com/yalelibrary/yul-dc-blacklight/pull/171

Screen Shot of Terminal

PDF of Screen Shot https://app.zenhub.com/files/242185115/6f293e1e-40d8-4b95-a62f-e155a063e510/download

[FCRodriguez7]

The test was made pending for the branch to pass other CI.