API Authorization for Engine

• Send Authorization Header
• Example https://gitlab.servus.at/aura/tank/-/blob/master/contrib/sample-cfg.yaml#L37
• Include session name ("engine") and secret (e.g. ENV-VAR AURA_ENGINE_SECRET), Add engine.ini config option.
• Include HTTP Header Authorization: Bearer engine:SECRET_STRING

Static sessions never expire and don't need to be refreshed.