support WASM by stubs and exclusions.

[davehorner]

I know there's complexities around wasm and iceoryx2. Instead of wraping iceoryx2 with
#[cfg(all(feature = "uses_iceoryx2", not(target_arch = "wasm32")))]

modify iceoryx2 to at least build under wasm32 target.
I'd be willing to contribute this work if there is interest.