MEDIUM: quic: inspect ALPN to install app_ops

Remove the hardcoded initialization of h3 layer on mux init. Now the
ALPN is looked just after the SSL handshake. The app layer is then
installed if the ALPN negotiation returned a supported protocol.

This required to add a get_alpn on the ssl_quic layer which is just a
call to ssl_sock_get_alpn() from ssl_sock. This is mandatory to be able
to use conn_get_alpn().
4 files changed