feature request: expose more s2n_quic_provider::message APIs

[dignifiedquire]

I am currently trying to implement my own s2n_quic::provider::io::Provider, which will be similar to the tokio one in s2n_quic_provider.

Trying to write this prototype, I am running into the issue that s2n_quic_provider::message::Storage and s2n_quic_provider::message::Message have some fundamental methods marked as pub(crate). This would force me to duplicate all of this logic in my implementation, which I would like to avoid.

So I wanted to ask if it is possible to make them public.

[dignifiedquire]

more specifically, I am trying to write

• impl tx::Socket<Message> for UdpSocket and
• impl rx::Socket<Message> for UdpSocket

with UdpSocket being a custom wrapper around tokio::net::UdpSocket.

[dignifiedquire]

I have made #2189 as a demonstration of the pieces I need