Invoke a function asynchronously

Argument list forwarded to the executor's call_export_with_args path. Each element is converted to the closest-fitting wasm value type: integers in [-2^31, 2^31) become i32, larger integers become i64, non-integer numerics become f64. Strings / arrays / null / booleans are rejected as 400 invalid_args. f32 cannot be selected from JSON unambiguously — write a guest wrapper that demotes from f64 if you need it.