feat: add binding for wasi_config_set_stdin_bytes

[ramilmsh]

Adding a binding for wasi_config_set_stdin_bytes

I've never worked with cgo before, so no idea if this is safe/free of memory leaks, but seems to have worked for me

[alexcrichton]

Thanks for the PR! I think this'll want some tweaks ownership-wise though. The wasi_config_set_stdin_bytes API is defined as taking ownership of its vector argument. That means you'll want to construct the vector with wasm_byte_vec_new_uninitialized and then copy the bytes from Go into the allocated vector, then pass that vector off to the API. That'll avoid using Cbytes and free here I believe.

You can see an example here of passing byte arrays from Go into Rust, and you can use wasm_byte_vec_copy to copy from Go into the Rust-allocated vector.

Also, would it be possible to write a test for this as well?