Provide the ability to deploy Atlantis without a domain associated to it

[JSNortal]

It would be useful to make the domain input optional to and allow for the module to either reserve a static external IP or take as an input.

It would make getting up and running a bit faster for testing purposes.

[bschaatsbergen]

@JSNortal thanks for taking the time to raise this issue 👍🏼
What are your thoughts on this? @kpocius

[kpocius]

Sounds doable, although I'd keep the reservation out of the scope of the module, much like it is now done with DNS records. Also, this needs to come with proper warnings that some potential security features will be lost (e.g. I don't see this setup working with IAP).

[steliossid]

Is it possible to use a reserved external static IP in GCP as the domain?