Add/implement domain name

[wiardvanrij]

We need to add a domain name. Multiple reasons:

• Looks nice
• Enables us to use SSL
• Required for SSO on ArgoCD due to the callback

I believe @GiedriusS was working on this already! :)

p.s. added the tag "only-doable-by-maintainers" as this is unfortunately a thing that requires extra rights (: