TLS Subscription fail and retry state
Adds new failed and retry states for TLS Subscriptions.
TLS Subscriptions can fail to renew or issue certificates due to many reasons outside of Fastly's control. We will now only retry issuing a certificate for 7 days past the existing certificate's not_after date or subscription creation, whichever is later. After that date, if no certificate can be issued, the subscription's state will change to 'failed' and Fastly will stop retrying.
If you fix the issue and want Fastly to retry issuing the certificate, set the TLS Subscription's state to 'retry', which tells Fastly to try to issue the certificate again.
Prior change: JavaScript SDK 1.5.1
Following change: CLI v8.0.1
