add tracing instrumentation

[Ruben2424]

This adds tracing to most connection relevant functions. This should make it easier to debug.

[seanmonstar]

It'd be nice if tracing could be optional. I was recently reminded of the desire for this in h2: hyperium/h2#713

[Ruben2424]

@seanmonstar, I added features for h3 and h3-quinn to enable tracing. What do you think?

[seanmonstar]

Looks good to me. For what it's worth, you can name it tracing. Under features in the Cargo.toml, it could be tracing = ["dep:tracing"]. I think something like that is cleaner, it doesn't need to include the prefix of the crate (like h3-) in its own features.

[Ruben2424]

Looks good to me. For what it's worth, you can name it tracing. Under features in the Cargo.toml, it could be tracing = ["dep:tracing"]. I think something like that is cleaner, it doesn't need to include the prefix of the crate (like h3-) in its own features.

I added the prefix because it confused me to have two crates with the same feature in one repo. When I call cargo test --all --features=tracing does it compile h3 or h3-quinn with the tracing feature. Or both?