Add automated WASI testsuite

[Robbepop]

Wasmi has WASI p1 support for a long time now, thanks to @OLUWAMUYIWA .

However, it is since in experimental state because it is missing automated tests. While we are certain that the WASI implementation kinda works due to empirical observation, we still want to have assurance about this in the form of automated tests via CI.

For this an official WASI testsuite even exists that we can simply use similar to how we use Wasm's official testsuite: https://github.com/WebAssembly/wasi-testsuite/tree/main

This issue is tracking this progress.
Resolving this allows us to label Wasmi's WASI support as stable.

cc @OLUWAMUYIWA