feat: V2 authn config + redis

[markphelps]

Re: #3831

This PR does the following:

• refactors authentication config to add session.storage with support for memory or redis atm
• implements redis authentication store
• removes cleanup for authentication storage as I think this can be handled implicitly by the session stores (ie delete expired tokens automatically via TTLs) we could probably still make the grace period a thing though.
• adds storage tests for the redis store using the existing (modified) auth testing harness

TODO

• implement TTL/auto cleanup in the memory session store
• wire up the redis store in grpc/authn server if configured

[GeorgeMac]

Its looking great. One naming thing.