feat: add is_enterprise boolean

[shaunwarman]

Edit: Just focus on is_enterprise boolean as an extra plan option and nothing more

[titanism]

Instead of all this, we should instead have is_enterprise Boolean, since pricing changes by enterprise customer (e.g. some require changes to the legal docs which costs more, or require custom deployments). We should not do an approach where plan is anything other than what it is now. I'll revisit this when I get more time, as other things will change too and most of this isn't really useful (yet).

[shaunwarman]

Updated to just focus on the is_enterprise boolean