* fixesopenziti/ziti#3356 adds www-authenticate headers
- www-authenticate headers are returned on 401s from API requests
- www-authenticate headers are returned during authentication to signal
addtional JWT bearer tokens needed (secondary ext jwt)
- adds support for additional headers on API errors
- adds SecurityTokenCtx for centralized security header processing
(legacy, jwt, etc.)
- adds SecurityCtx for centralized identity, auth policy, MFA handling
- refactors existing JWT authentication methods (oidc, legacy) to use
centralized processing where possible
Andrew Martinez