tight dependency to y-k8s-ingress-hosts

[solsson]

ystack's y-k8s-ingress-hosts is core to dev clusters. Since Yolean/ystack#76 it understands the dns-hint-ip annotation, but that's an impelentation detail. We however don't want to bundle the functionality of y-k8s-ingress-hosts, and y-cluster should remain distributable as single binary. We could provide some kind of install help that also facilitates passwordless sudo (install to a bin path where only root can update the binary).

[solsson]

A strong +1 found in ystack Yolean/ystack@4706946

We should call it DevHosts as the manipulation of /etc/hosts files should only be used for dev purposes.

The || echo WARNING in ystack hints that we need to support an env such as Y_CLUSTER_DEV_HOSTS_MODE that can tell the check to require successful hosts update or allow fail with warning. Default should be require.