Accessibility Updates to Super Rentals

[toddjordan]

The goal of this task is to take the updates made to the super rentals example in PR ember-learn/super-rentals#121 and apply them to the tutorial

The following changes would be required:

• Add aria-hidden and tab-index -1 to location-map component to hide it from screen readers
• Add a label tag to the search input in list-filter.hbs
• Add alt text to rental image in rental-listing.hbs
• Install ember-a11y-testing addon and add config, as well as add auditing to test cases
• Fix link-to in https://guides.emberjs.com/release/tutorial/routes-and-templates/#toc_adding-a-banner-with-navigation

[toddjordan]

Had a couple open comments on the super-rentals PR, and wanted to get resolution on those, as well as call out each specific tutorial page to make the above updates before opening this to "help wanted"

[toddjordan]

Targeting a PR for these items for Thursday (Global a11y day)