Constant data_encoding::BASE64URL

pub const BASE64URL: &'static Padded = BASE64URL_IMPL

RFC4648 base64url encoding

This encoding is a static version of:

assert_eq!(BASE64URL, &Builder::new(
    b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")
        .pad(b'=').padded().unwrap());

It is conformant with RFC4648.