Add integration to existing authentication/security libraries

[kamilkloch]

Now that tapir's endpoint has gained a dedicated authentication/security channel it would be nice to integrate it with the existing backend-specific libraries. I found the following libraries which do the job for one specific backend:

• softwaremill's https://github.com/softwaremill/akka-http-session ;)
• https://github.com/hgiddens/http4s-session ("Heavily based on the awesome akka-http-session.")
• tsec for http4s: https://jmcardon.github.io/tsec/docs/http4s-auth.html
• https://github.com/http4s/http4s-session

In fact, it looks like a lot of work has been poured into https://github.com/softwaremill/akka-http-session. Perhaps it would be possible to re-use it and abstract over the backend.