Experimental: Use Wasm exceptions for SjLj when using V8

[syrusakbary]

Support WASIX longjmp/setjmp via Wasm exceptions using --v8.

We'll need to modify wasix-libc to use Wasm Exceptions when calling longjmp/setjmp (so longjmp/setjmp can be called using Wasm exceptions, and not using asyncify as we were doing until now).

Idea:

1. Been able to compile this file with WASIX (using Wasm exceptions)
   https://github.com/wasix-org/wasix-libc/blob/main/examples/longjmp.c
2. Run the generated wasm file (that has exceptions on it) with Wasmer + V8

Some resources: https://emscripten.org/docs/porting/exceptions.html#webassembly-exception-handling-based-support

Files: https://github.com/emscripten-core/emscripten/blob/main/system/lib/compiler-rt/emscripten_setjmp.c