Spike - investigate how to enable/disable tracing on a per-module basis

[Notgnoshi]

Motivated by #12 (comment)

Having optional tracing is great, but as the project grows, adding tracing around everything will get quite verbose. We should find a way to let a developer enable tracing only for the modules they want.

We'd probably want to use https://docs.rs/tracing-subscriber/0.3.18/tracing_subscriber/#layers-and-filters for this?

Would this be defined entirely in user code? Or are there hooks we have to provide in the library itself? Regardless, we'll want to provide documentation to show users/developers how to adjust things.