[QUIC] Add support for SslCertificateTrust

[rzikm]

SslStream supports some control over which certificates are to be considered as trusted. See SslStreamCertificateContext.Trust and e.g. #55104.

While we might not be able to force the QUIC TLS backend to send the trusted list as part of TLS handshake, we can still implement the certificate validation part of the above mentioned PR. The prerequisite to that is making the SslStreamCertificateContext.Trust public (Or at least visible to S.N.Q), same for internal members of SslCertificateTrust

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Issue Details

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SslStream supports some control over which certificates are to be considered as trusted. See SslStreamCertificateContext.Trust and e.g. #55104.

While we might not be able to force the QUIC TLS backend to send the trusted list as part of TLS handshake, we can still implement the certificate validation part of the above mentioned PR. The prerequisite to that is making the SslStreamCertificateContext.Trust public.

Author:	rzikm
Assignees:	-
Labels:	area-System.Net.Security
Milestone:	-

[ghost]

Tagging subscribers to this area: @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

Issue Details

---

SslStream supports some control over which certificates are to be considered as trusted. See SslStreamCertificateContext.Trust and e.g. #55104.

While we might not be able to force the QUIC TLS backend to send the trusted list as part of TLS handshake, we can still implement the certificate validation part of the above mentioned PR. The prerequisite to that is making the SslStreamCertificateContext.Trust public.

Author:	rzikm
Assignees:	-
Labels:	area-System.Net.Quic
Milestone:	-

[rzikm]

Tentatively assigned to Future, this probably is not critical for 7.0 but would be good for consistency.