test(s2n-quic-transport): add transmission interest debugger

[camshaft]

Description of changes:

This change adds a transmission interest debugger which prints out which component is wanting to transmit and what type of interest it has. I was using it in testing awhile back and thought it would be useful to have.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[WesleyRosenblum]

How would one use this?

[camshaft]

Anything that implements transmission::interest::Provider can be queried. So for example, you can query the connection:

let _ = self.transmission_interest(&mut transmission::interest::Debugger);

and you get something like this:

  /home/cameron/Projects/aws/s2n-quic/quic/s2n-quic-transport/src/stream/stream_container.rs:649:19 - NewData
  /home/cameron/Projects/aws/s2n-quic/quic/s2n-quic-transport/src/connection/local_id_registry.rs:725:15 - None
  /home/cameron/Projects/aws/s2n-quic/quic/s2n-quic-transport/src/connection/peer_id_registry.rs:669:15 - None