Validate the IP address in the certificate for DNS-over-TLS in strict mode when GnuTLS is used. As this is not yet the case in contrast to the documentation.
Instead of having a context and/or trusted CA list per server this is now moved to the server. Ensures future TLS configuration options are global instead of per server.
This provides basic OpenSSL support without optimizations like TCP Fast Open and TLS Session Tickets.
Notice only a single SSL library can be enabled at a time and therefore journald functions provided by GnuTLS will be disabled when using OpenSSL.
Fixes#9531
