Accessibility: Tours dropdown menu

This is actually a core issue, but recording it here so that it's a known issue as regards this plugin.

The dropdown menus off the adminbar do not work well with screen readers running; the keyboard handlers don't fire. So adding the tours to a dropdown menu in the adminbar does not solve the problem of providing access to screen readers.

There is an open issue for this, and I've milestoned it for 6.5, so this could change - but it's been a really hard problem to solve while maintaining backwards compatibility, so it's not a sure thing.

See: https://core.trac.wordpress.org/ticket/34668

Start by reading the plugin issue and WordPress core ticket 34668, which tracks the admin-bar dropdown keyboard-handler problem. Confirm whether the core issue has been resolved and determine what plugin integration, if any, is still needed for Tours to be accessible to screen readers. Done means the Tours dropdown is usable with screen readers without breaking backwards compatibility.

Written by the indexing model from the issue text.