Feat: ARI support?

[olmari]

I'd love to have an ARI support with Acme-tiny.

Further this would kind of split into 2 things, first would be getting the ARI information from an ACME server, while this could be considered not exactly an scope of Acme-tiny, but the data how an ARI "URL" is calculated needs still to exist for the second point that definitely would be Acme-tiny's scope.

Secondly when new certificate is ordered, with ARI Acme-tiny can send information back which certificate the request replaces.

This would be best possible way to handle sudden need of certificate replacement now as OCSP is no more supported by Lets Encrypt for example.

Technical details how to implement can be found from example here: An Engineer’s Guide to Integrating ARI into Existing ACME Clients.

Thank you for considering this!

This is essentually same feature request I made for #294 ssrlive/acme-tiny#1