SecureRequestCustomizer() for HTTP3

[edgecase14]

Jetty version(s)
12.0.9
Enhancement Description
I am using this to get SSL client certificate on HTTP1.1/2 server side. I don't see a way to do this with HTTP3 although mutual TLS auth is working.

[lorban]

It should be possible to get the peer's certificate with HTTP3 but this currently isn't exposed.

Thanks for filing this issue, we're going to fix this.

[sbordet]

See #11892.