Chore: Add browser integration tests

[JannikStreek]

Further Notes

Currently we primarily use unit tests. Some browser tests would be nice, as the javascript part is getting more and more.

Possible Implementation

https://github.com/elixir-wallaby/wallaby

[PragTob]

Love wallaby, not sure how active/applicable to Live view it is (it should be), but it was designed and built in a time before ubiquitous live view.

The phoenix_test library is following an interesting approach which I like: https://github.com/germsvel/phoenix_test - also still seems to be active :)

That said, at Remote (and other companies that I know/heard of) they used java script testing utilities (much better developed) like cypress. Then of course setup etc. comes much harder again (since you don't have the access to the database directly and so setup is truly all through the browser which is a lot slower).