Function cppconnect6::cppbind::ffi_test::test_echo_cppeval

#[no_mangle]
pub extern "C" fn test_echo_cppeval(
    turn: CInt, 
    boards: *const CInt, 
    len: CInt, 
    callback: Callback, 
    allocator: AllocatorType<CFloat>
) -> RawVec<CFloat>

Get boards and callback then return the evaluation from CppEval