Add new Hetnzer provisioner to operator

There is a working Hetnzer provisioner which we can add to the operator now.

Expected Behaviour

Users on Hetzner should be able to use the inlets-operator

Current Behaviour

It's not yet available

Possible Solution

Adding it to the controller should be a case of:

  1. Find all references of "EC2" or "DigitalOcean"
  2. Copy/paste
  3. Test end to end with exposing a service, accessing it and then deleting the service to check the VM is removed.

Finally, update the arkade app to take the new flag via --provider

Requested in #44