Add s2n-quic support

[rklaehn]

Very WIP

This performs very badly for the bidi_seq part of the benchmark.

Run like this:

cargo test s2n_quic_channel_bench --release -- --nocapture

...
running 1 test
RPC seq 2_030 rps                                                               
RPC par 33_473 rps                                                              
bidi seq 61 rps                                                                 
test s2n_quic_channel_bench ... ok
...

Not sure what is going on. This test is just pushing a lot of msgs over a single channel, so it should be faster than the RPC par test.

[camshaft]

I'll try to take a look at this soon.