`listen` to `quic` AND `proxy_protocol`

#=== reverse proxy config ===
stream {
  map $ssl_preread_server_name $upstream {
    foo.example.org  127.0.0.1:8443;
    bar.example.org  10.11.12.13:8443;
    # ...
  }
  server {
    listen 443;
    proxy_pass $upstream;
    ssl_preread on;
    proxy_protocol on;
  }
  server {
    listen 443 udp reuseport;
    #    proxy_pass $upstream;
    #    ssl_preread on;
    ### BUG: ssl_preread is broken
    ### WORKAROUND: disable until implemented, only pass to single upstream works
    proxy_pass 127.0.0.1:8443;
    #    proxy_protocol on;
    ### BUG: proxy_protocol on quic is broken
    ### WORKAROUND: disable until implemented
  }
}

#=== server config ===
http {
  server {
    server_name foo.example.org;
    listen 127.0.0.1:8443 ssl proxy_protocol;
    listen 127.0.0.1:8443 quic;
    add_header Alt-Svc 'h3=":443"; ma=86400';
    # ...
  }
}

Syntax: 	listen address[:port] [default_server] [ssl] [http2 | quic] [proxy_protocol] ...