Support whitespaces in data

[RazrFalcon]

let (data, _) = try "data:text/plain;base64,\nAAECA3Rl\nc3QK".dataURIDecoded()
print(String(bytes: data, encoding: .utf8)!.debugDescription)

This code prints \nAAECA3Rl\nc3QK, while it should print \0\u{01}\u{02}\u{03}test\n