zeroize: add support for `wasm`'s `v128` SIMD register

[brxken128]

This PR adds support for zeroing wasm's v128 register. The module is named after the core::arch module, but it does require that target_family = "wasm" so I'm unsure of which naming scheme to stick with - I'm not too familiar with WASM as a whole to be honest.

I'll leave this as a draft until #967 is ready and merged, as the support for zeroing SIMD registers for ... notice will need updating.