Add mTLS testing for rustls

[toidiu]

Problem:

#1725 adds testing for mTLS but only enables it for s2n-tls on non-windows platform. We should also build the rustls tls provider and test as part of integration testing.

Solution:

https://github.com/aws/s2n-quic/tree/main/examples/rustls-mtls has setups up mTLS with rustls but uses ServerConfig and has to set a bunch of options to work with quic. This can be error prone so maybe we want to expose a with_client_auth for the rustls provider as part of this.

Requirements / Acceptance Criteria: