feat(unstable): ALPN config in listenTls

This commit adds the ability for users to configure ALPN protocols when
calling `Deno.listenTls`.

cli/dts/lib.deno.unstable.d.ts

@@ -1001,6 +1001,16 @@ declare namespace Deno {
     options?: StartTlsOptions,
   ): Promise<Conn>;
 
+  export interface ListenTlsOptions {
+    /** **UNSTABLE**: new API, yet to be vetted.
+     *
+     * Application-Layer Protocol Negotiation (ALPN) protocols to announce to
+     * the client. If not specified, no ALPN extension will be included in the
+     * TLS handshake.
+     */
+    alpnProtocols?: string[];
+  }
+
   /** **UNSTABLE**: The `signo` argument may change to require the Deno.Signal
    * enum.
    *

runtime/js/40_tls.js

@@ -51,13 +51,15 @@
     keyFile,
     hostname = "0.0.0.0",
     transport = "tcp",
+    alpnProtocols,
   }) {
     const res = opListenTls({
       port,
       certFile,
       keyFile,
       hostname,
       transport,
+      alpnProtocols,
     });
     return new TLSListener(res.rid, res.localAddr);
   }

runtime/ops/tls.rs

@@ -300,6 +300,7 @@ pub struct ListenTlsArgs {
   port: u16,
   cert_file: String,
   key_file: String,
+  alpn_protocols: Option<Vec<String>>,
 }
 
 fn op_listen_tls(
@@ -318,6 +319,11 @@ fn op_listen_tls(
     permissions.read.check(Path::new(&key_file))?;
   }
   let mut config = ServerConfig::new(NoClientAuth::new());
+  if let Some(alpn_protocols) = args.alpn_protocols {
+    super::check_unstable(state, "Deno.listenTls#alpn_protocols");
+    config.alpn_protocols =
+      alpn_protocols.into_iter().map(|s| s.into_bytes()).collect();
+  }
   config
     .set_single_cert(load_certs(&cert_file)?, load_keys(&key_file)?.remove(0))
     .expect("invalid key or certificate");