[enhancement] Use tracing instead of log

[ActuallyHappening]

I am consuming the library version of cargo-leptos (with a few patches ofc) and logs coming from the library don't have a target. Porting to tracing should be transparent to users, but allow for library users like me to benefit from all of tracings features. Admittedly not many people are using this as a library, but it is much cleaner in cargo xtask-like rust scripts than spawning subprocesses, if only for the guarantee that the same wasm-bindgen version is used across the rust-compilation / binary invocation boundary.

[ActuallyHappening]

OK I'm going to work on a PR to this effect