Added a wrapper class around \Firebase\JWT\JWT and \Firebase\JWT\Key

[MichaelSowah]

Added a wrapper class around \Firebase\JWT\JWT and \Firebase\JWT\Key to help avoid plugin conflicts such as https://github.com/usefulteam/jwt-auth/issues/82

[sun]

Thanks a lot for contributing this change, @MichaelSowah! 🙂

As I'm fairly familiar with the inner workings of the class loader, I'm skeptical about the proposed solution. Let's discuss in https://github.com/usefulteam/jwt-auth/issues/82#issuecomment-1438840613 first. 👍