add more ci for wasm and embedded targets

[KodrAus]

This PR does some more work on our CI to explicitly test wasm through Node and that we build for a proper no-std target. It also uses cargo-hack instead of manually listing out feature combinations to test.

[KodrAus]

I've ended up bumping our MSRV to 1.46.0 to support some new dev infrastructure. It would be nice if we could pull in dev dependencies for specific targets to avoid this, but 1.46.0 is now a year old, is available in Linux package managers, and opens up a bunch new const-fn opportunities for the crate.