Macro impl_virtualfile_on_std_streams

macro_rules! impl_virtualfile_on_std_streams {
    ($name:ident { readable: $readable:expr_2021, writable: $writable:expr_2021 $(,)* }) => { ... };
    (impl AsyncSeek for $name:ident) => { ... };
    (impl AsyncRead for $name:ident) => { ... };
    (impl AsyncWrite for $name:ident) => { ... };
}