Allow for connecting to a endpoiunt by domain.

[scrolledtoofar]

I'm currently trying to set this up on my own wireguard instance on a server with a non static ip.
I can connect to it using a domain with the desktop app but gluetun requires an ip to be set.
Is it possible on to add connecting by domain?

[github-actions]

@qdm12 is more or less the only maintainer of this project and works on it in his free time.
Please:

• do not ask for updates, be patient
• 👍 the issue to show your support instead of commenting
  @qdm12 usually checks issues at least once a week, if this is a new urgent bug,
  revert to an older tagged container image