feat: manage hostname / ip address exposed by K8 LoadBalancer service

[qdzlug]

Is your feature request related to a problem? Please describe.
Within the ingress_controller project, we receive the hostname and/or IP address of the external IP that we are assigned based on the K8 LoadBalancer object. The hostname is key for the cert-manager function which handles the certificate issuance (to start with, we issue self-signed certs currently). However, some LoadBalancer implementations (such as metallb) only provide an IP address and no hostname. To get around this, we currently prompt for and use a FQDN, with the understanding that the user needs to either create a DNS record or update their hostfile to connect the FQDN with the IP address they are using.

Describe the solution you'd like
This should be seamless to the user, and should be able to follow logic that:

1. Checks for the presence of a hostname associated with the IP address (if only an address is given).
2. Provide instruction to the user as to what steps need to be taken if no FQDN is bound to the IP address.

Additionally, the logic should include a place where an outside DNS provider can be called from the stack to create a record linking the FQDN and the IP address. Note that we do not need to implement this, merely make sure we don't make any design decisions that prohibit this from being done.

Describe alternatives you've considered
None.

Additional context
None.

[qdzlug]

#167 addresses DO, Linode in addition to AWS support. Additional support is WIP (for kubeconfig deploys)