Support OpenSSL 3 & JWT 2.2

[pboling]

• Compatibility with JWT 2.0 (from Aha's fork)
• Compatibility with JWT 2.2 (from Discourse's renamed fork)
• Compatibility with OpenSSL 3.0 (from GitLab's vendored fork)
• some additional fixes by me.

Above are three major projects that use forks of this gem. My hope is that instead of diverging into a multi-verse of same-but-different gems we can standardize on one!

(Includes renaming the gem - I don't expect this to get merged, but maybe it will generate discussion)

@mbleigh Could we, the community, take over this gem, and move it into the omniauth organization?

[pboling]

I've released these changes as omniauth-jwt2! 🥳