karma-chrome-launcher doesn't support newer chrome yet

This should be used by every app, so move it here to avoid duplication.

In case we try to register the element multiple times under the same name
just do nothing. This allows us to not register things by default and
register under the same name in multiple places where needed without
coordination.

These allow linking multiple AbortControllers and ceate a timeout abort signal.

For example in case you want to abort a fetch in case

(1) the UI element gets removed
(2) a newer request replacing this one gets started
(3) a timeout happens because the fetch takes too long

createLinkedAbortController() allows merging multiple signals into one
and createTimeoutAbortSignal() allows creating a singal that auto aborts
after some time passes.

This generalizes the features of the events module and should replace it in the long run.

It allows simple pub/sub and retained events without a centralized instance.

This makes responsivness of single selects work better.

See https://stackoverflow.com/questions/30788171/wrap-selected-text-with-select2

See https://gitlab.tugraz.at/VPU/Apps/Library/issues/42

It has a new enough firefox now

See https://gitlab.tugraz.at/VPU/WebComponents/datatableview/issues/2

While this will never work with old Edge it makes things easier during testing
where we can't set an id on the script tag. And we still don't know if supporting
old Edge is even needed.

We should try to avoid changing the DOM directly and these helpers go against that.
They both just add two lines of code which we can just copy around if needed.

This is a common source for errors and we currently fall back to a relative path
which happens to work locally but not on the server.