Function base64_url::unescape_u8_slice_try_in_place

pub fn unescape_u8_slice_try_in_place<S: ?Sized + AsMut<[u8]>>(
    base64_url: &mut S
) -> Cow<[u8]>

Unescape Base64-URL data to Base64 data and try to do it in-place. It is unsafe because the conversion is not concerning with Base64 decoding. You need to make sure the input Base64-URL data is correct by yourself.