This has proper support for rollup while providing the same API.

This is what open-wc recommends now and uses in their @open-wc/testing package

Use tdd in all cases to be more consisstend.
Also since last year we can use chai with rollup directly, so
do that everywhere instead of relying on karma-chai injecting
it in to the global scope.

We only want to export it in the package entry point and not
the generated bundle.

The demo now registers our web components lazily with a unique name
so that two different apps using the same underlying web compontens
don't clash.

This also disables auto registering and leaves that to the user.

This duplicates the language switcher on the tugraz.at site.

Compared to the previous implementation we now show the next language
and use the translations for the next language, so that users only knowing
english can understand it.

In case of more languages we just cycle through them, which isn't ideal but
good enough for now.

Also use the same reference for removing the event handler, bind creates a new one.