Refactor cert approval check to account for existing cert

Currently if Up is waiting on a cert approval, and you `C^`, the next run will not output `Check your email to approve the certificate, resulting in a `up stack apply` attempting to use an unapproved certificate for the domain.

`createCerts()` uses some local state from `RequestCertificate` to see if we're waiting or not, it should just check pending certs instead to allow for both scenarios