Experiment with the Stack-Switching proposal

[vouillon]

There is some ongoing work in wasmtime and Wisard to support both Wasm GC and the Stack Switching proposal. It would be interesting to provide to test some benchmarks with these engines. They do not support JavaScript, so we would need to modify our runtime.

There is already a draft implementation #52.

Our effect examples do not use much functionalities from JavaScript: some output to stdout, int64 bigarrays for random numbers. As a quick hack, it should be rather easy to trim down the runtime to implement just these functionalities in Wasm and remove any other JavaScript dependency.