Testing for all supported platforms.

[tobz]

We should invest some time in seeing if we can get our test suite to actually run for all platforms that we target/support.

We already target Linux, Windows, and macOS on 86_64, which is good. We should theoretically be able to target WASM/WASI via cargo-bindgen-wasm and cargo-wasi and I think those could just execute on Linux x86_64 runners.

The tricker bit is if we wanted to test on another CPU architecture, as the free tier Github Actions runners have no ARM/ARM64 support, and setting up our own runners would be difficult/cost prohibitive... unless there's some sort of 3rd party runner service I don't know about.

[tobz]

#54 is an example of an alt platform that could use CI support (MIPS) but currently has no obvious approach to do so.

[messense]

Cross maybe useful: https://github.com/rust-embedded/cross#supported-targets