Function find_hax_engine

pub(crate) fn find_hax_engine(message_format: MessageFormat) -> Command

Dynamically looks for binary ENGINE_BINARY_NAME. First, we check whether [HAX_ENGINE_BINARY] is set, and use that if it is. Then, we try to find ENGINE_BINARY_NAME in PATH. If not found, detect whether nodejs is available, download the JS-compiled engine and use it.