Enable deployment without the `mn create-acme-account` command (documentation or new CLI tool)

[msgilligan]

A user deploying from a docker image or a released native-image binary may not have access to a Micronaut project source repository to run the mn create-acme-account command.

The documentation describes how openssl genrsa -out /tmp/mydomain.com-key.pem 4096 can be used in place of the mn create-key command. It also says:

Certbot or many of the other tools out there can also accomplish this step if you dont want to use this tool.

My experience is that Certbot is hard to use "a la carte". I would like to see a standalone (native-image) tool that can just do the create-acme-account command. (I suppose you might also need delete-acme-account and perhaps create-key for people that don't want to use openssl)

Alternatively If there is another common/readily-available tool, the documentation could be updated to reference it.