the scoped mixin no longer depends on it directly

And adjust for the import changes

It has new API which we want to use.

This makes it use those packages from npm instead of locally, not
sure why this was added.

Newest Ubuntu switched Firefox to a snap, which breaks karma.

Try to use playwright to download and cache firefox/chromium
and use those for karma.

Compared to puppeteer where we did this some time ago this caches
the browsers globally, and only downloads them when we start the tests.