Accessibility Improvements

[qqmyers]

Overview of the Feature Request
QDR has been working to improve Accessibility in Dataverse, primarily using the Deque Axe plugin to identify issues. The changes made significantly reduce the number of issues reported. For example, the main page on demo.dataverse.org lists 89 issues whereas the main page of a test server with the updates reports only 26 issues and all of these appear to be spurious color contrast issues (Axe flags any elements where there is a gradient background or an overlapping element, even if the displayed contrast is OK). There are similar reductions in almost all pages.

A PR to follow.

Any related open or closed issues to this feature request?
There are a wide range of accessibility issues including #7523 which is broad. Earlier accessibility issues could be reviewed to see if they are still relevant after the changes included in the PR for this issue.

In general, testing with Axe involves having the page and/or pop-ups involved displayed, so it is easy to miss issues if you don't open a menu, are in a different state (logged in/out, edit versus create versus view modes, with/without custom header/footers, etc.

There are some issues that look to me like they are due to PrimeFaces problems that are not easy to solve without editing their classes, including:

• Interactive controls must not be nested - issue with PrimeFaces tabs
• ARIA hidden element must not contain focusable elements - PrimeFaces dismissable alert message
• All page content should be contained by landmarks - PrimeFaces datepicker adds elements outside main content area and doesn't add a landmark role.
• ARIA hidden element must not contain focusable elements - PrimeFaces selectCheckboxMenu