Base64Url throws MalformedInput when status InvalidData is expected

[gfoidl]

The api are thought to be exception-less, that why they use OperationStatus.
Base64.Url can throw a FormatException (malformed input) in some cases. Maybe it's better to not throw the exception and just return OperationStatus.InvalidData?

[gfoidl]

Ups, I think I've looked to the wrong overload, namely to one that returns byte[], so the behavior is OK.

[gfoidl]

There's still one pattern where this is hit, but a rare pattern. Though it should behave correct.
If input is A (a single character). It's not valid base64Url, but it should result in InvalidData instead of throwing.