implement unit and end-to-end testing

[r03ert0]

https://testing.quasar.dev/

[ntraut]

maybe we could wait a bit before implementing this because the ui is still not well stabilized so it can slow the development if at each we make changes to the ui we also need to adapt the tests...

[r03ert0]

What I had in mind with this issue, more than to start writing tests, was to set up the pipeline, even if there's no tests or very simple tests. Basically, get working what's described here https://testing.quasar.dev/