[CoreDNS] Automatic Certificate Management in TLS plugin

[nate-double-u]

CoreDNS is a cloud-native DNS server with a focus on service discovery. While best known as the default DNS server for Kubernetes, CoreDNS is capable of handle many other scenarios such as severing DNS through HTTPS/TLS. As HTTPS/TLS requires valid certificate any renewal of corticate periodically, an automation (e.g., through ACME protocol) will minimize the manual maintenance need. This project is to provide certificate management automation in TLS plugin of CoreDNS.

Mentor(s): Yong Tang (@yongtang) Paul Greenberg (@greenpau)

https://github.com/cncf/mentoring/blob/main/summerofcode/2022.md#automatic-certificate-management-in-tls-plugin