Make HTTP/3 Quic skip certificate verification

The current implementation of HTTP/3 Quic in Nighthawk reuses Envoy's `Http3::ConnectionPool` which has a hardcoded Quic's `EnvoyQuicProofVerifier`. This means that a Quic connection can only be established if the requested hostname matches the one in the leaf server certificate.

This is different from how Nighthawk handles HTTPs with H1/H2 where certificate verification is skipped. The simplest solution might be to create our own instance of the H3 connection pool with the `TestProofVerifier` from [here](https://github.com/envoyproxy/envoy/blob/e85a7f408c7baee8e1ed4af39a647c98ee5f2215/test/common/quic/test_proof_verifier.h#L9).