email_server: Re-implement TLS configuration

• Use LetsEncrypt component to perform TLS certificate copying instead of custom implementation.

• Use two components to copy the certificates to dovecot and postfix separately.

• Add support for multiple domains using SNI. Provide all the certificates. Use primary domain's certificate as the fallback certificate.

• Drop the diagnose/repair approach due to its complexity.

mentioned in merge request !2148 (closed)

assigned to @jvalleroy

Merged. This simplifies the code quite a bit. I also confirmed that the certificates are in the expected location after installing.

closed