Various WASM wrappers around Rust crates

It is split up into a number of internal packages, namely utilities -

• wasm-crypto Various hashing functions, sr25519 & ed25519 crypto

These are split from the polkadot-js/util repo where it is heavily used as part of @polkadot/util-crypto. (There JS fallbacks are available for some interfaces, e.g. hashing, but for sr25519 WASM is the only interface). Since these don't undergo massive changes on a daily basis and has a build overhead (WASM compilation & optimisation), it is better managed as a seperate repo with a specific CI configuration.

Contributions are welcome!

To start off, this repo (along with others in the @polkadot family) uses yarn workspaces to organise the code. As such, after cloning, its dependencies should be installed via yarn, not via npm; the latter will result in broken dependencies.