Rename 'site ssl' to 'site ssl-verify'

[kirtangajjar]

ee site ssl command is causing confusion among new v4 users. They either assume it will add SSL to a non-SSL site or they think it will be required to run every time after any SSL site creation.

Hence to clarify what ee site ssl does, it is better if we rename it to ee site ssl-verify. If the current command does both verify SSL when using the DNS method and renew if it's present, we can create another command ee site ssl-renew and call the same function internally.

Also, it would be great if we would be able to track if DNS challenge verification is pending on a site. We can add this info in site_meta and only allow ee site ssl-verify if DNS verification is pending.