Playground JavaScript/WASI adapters

@ruby/wasm-wasi 2.10.1
Copyright (c) 2022 Yuta Saito. MIT license: ruby-wasm-MIT.txt
Source: https://github.com/ruby/ruby.wasm
Used by the Ruby Playground.

@bjorn3/browser_wasi_shim 0.4.2
MIT license: browser-wasi-shim-MIT.txt
Source: https://github.com/bjorn3/browser_wasi_shim
Used by the Ruby and C/C++ playgrounds.

The adapters are bundled and minified; their upstream code is not otherwise
modified. WASM binaries and the C/C++ compiler are downloaded separately from
jsDelivr, not redistributed in this repository.
Ruby's own license: https://www.ruby-lang.org/en/about/license/
The C/C++ compiler is browsercc 0.1.1 (MIT):
https://github.com/BertalanD/browsercc
Build instructions: scripts/playground-runtimes/README.md in the site repository.