JAWS: JSON Web tokens

Extracted from yacme as a starting point.

Built on RustCrypto

No OpenSSL depedency.

Strongly typed tokens.

Features

1. Strongly typed, wherever possible. The types in this crate should accurately model only the valid states for a JWT, and should make misuse of this JWT very difficult. If there are "foot guns" or places where the type system and API interface do not accurately represent the state of JWTs, I'd like to know and attempt to correct them.
2. Construct a JWT with a potentially custom payload and custom headers, but with strongly typed support for the registered claims and headers.
3. Broad support for cryptography algorithms supported in RustCrypto.
4. Easy API interface, which produces simple and ergonomic code.