Bug 1897008

In PR https://github.com/openshift/console/pull/7193 we disabled the Cypress a11y check for "aria-hidden-focus" until we can correctly implement: https://dequeuniversity.com/rules/axe/3.4/aria-hidden-focus?application=axeAPI

We need to correctly add "aria-hidden='true'" to the app root element when a Modal is launched.  This is done via Modal.setAppElement(document.getElementById('app')) (frontend/public/components/factory/modal.tsx:line 26).  After that is done we also need to ensure that children elements of the app root do not have [keyboard] focus:

"According to the fourth rule of ARIA, aria-hidden="true" should not be used on a focusable element. Additionally, since this attribute is inherited by an element's children, --->it should not be added onto the parent or ancestor of a focusable element. <----"

For example, if any of the child elements of our main app root context <div> have any of these properties, they will fail the "aria-hidden-focus" a11y check.

The following examples FAIL the aria-hidden="true" elements do not contain focusable elements rule:

Focusable off screen link.

  <div aria-hidden="true">
    <a href="/" style="position:absolute; top:-999em">Link</a>
  </div>

Focusable form field, incorrectly disabled.

  <div aria-hidden="true">
    <input aria-disabled="true" />
  </div>

aria-hidden can’t be reset once set to true on an ancestor.

  <div aria-hidden="true">
    <div aria-hidden="false">
      <button>Some button</button>
    </div>
  </div>

Focusable content through tabindex.

  <p tabindex="0" aria-hidden="true">Some text</p>

Focusable summary element.

  <details aria-hidden="true">
    <summary>Some button</summary>
    <p>Some details</p>
  </details>