Find classloader-safe solution for jwt tokens

[artem-v]

Current solution with jjwt doesn't work in isolated classloaders. There was issue and attempt to fix it, but it didn't solve a problem. Main problem is this method: io.jsonwebtoken.lang.Classes.forName(), major concern - jjwt has some custom class-loading logic.

In this ticket, find solution for jwt tokens that would be classloader safe, that would do just jwt job and that's it, without messing up with classloaders.