OpenSSL error - unknown certificate type when using SLH-DSA-* certificates

[rzikm]

Attempts to use SLH-DSA-* certificates will cause SslStream handshake attempts to fail with

      ---- System.Security.Authentication.AuthenticationException : Authentication failed, see inner exception.
      -------- Interop+OpenSsl+SslException : Using SSL certificate failed with OpenSSL error - unknown certificate type.

The reason seems to be because OpenSSL common provider does not advertise for the SLH-DSA-* signature schemes in its TLS-SIGALG capability

https://github.com/openssl/openssl/blob/0c679f556669e32499a827a081afe3bcf973c9ad/providers/common/capabilities.c#L315-L320

Since the Relevant RFC is still in draft state, this is not unexpected, but until OpenSSL introduces these, it is not going to be possible to use these certs with SslStream.

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[rzikm]

tracked by OpenSSL issue openssl/openssl#28026