Requires two crates to be useable

[rylev]

There might be some use of just win_etw_macros or just win_etw_provider, but most likely you'll need both. It would be much nicer if we took a book from the serde playbook and had one crate reexport the macros (behind a feature flag).

[dependencies]
serde = { version = "1.0", features = ["derive"] }