Jwt.JWT allows parsing tokens with json serialization

[simo5]

According to RFC 7519 only the compact serialization can be used for a proper JWT token.
Jwcrypto accepts any JWS/JWE token for parsing.

While this not a problem per se, people may want to reject even the ability to parse a non-compact serialization to reduce potential attack surface.

Provide a "strict" or "serialization" option when instantiating a JWT so that this aspect can be controlled.