Utilities `TokioIo` from [hyper-util](https://github.com/hyperium/hyper-util).
This code is mainly to make TokioIo compile under wasm.
A [PR](https://github.com/hyperium/hyper-util/pull/218) has been submitted to hyper-util. When it is merged, this repo will be archived.
Same as `hyper-util`, licensed under the [MIT license](./LICENSE).