* chore: run a11y audits on protractor
* Fixes accessibility issue in grid-list with `role="listitem"`
* Adds protractor plugin to run aXe-core accessibility audits
* Fixes a bunch of a11y issues in the e2e app to make the aXe audits green
* Force menu y-positions because viewport might be different on Selenium browsers.
* Navigiation links should be hidden by default because those can interfere with the tests.
Paul Gschwendtner