TLS ALPN support

[yearsyan]

Feature request

I thiink it is necessary to support alnp. For example, if a developer want to create a http2 server, alpn can make handshake quicker.

[kitsonk]

ALPN would need to be implemented as part of HTTP/2, so effectively duplicate of #3995.

[lucacasonato]

@kitsonk Not per se - if the HTTP/2 server is Rust based, then an implementation of ALPN for Deno.connectTls or Deno.listenTls would need to happen separately from HTTP/2 right?

[kitsonk]

I mean we wouldn't have to implemented ALPN to implement HTTP/2, but it doesn't make sense... the whole thing should be addressed as one (likely along with moving HTTP/1.1 into Rust as well which is something we said we were going to have to do).

[yearsyan]

@kitsonk I think an implementation of ALPN for Deno.connectTls or Deno.listenTls is good for developer who want to create a protocol over tls, HTTP/2 is not the only protocol needs ALPN.