Extend and refine example values in Tank API

Parent: [EPIC] Future-proof AURA API (aura#192)

The examples in the Tank API hold missing values.

E.g. the example for the endpoint POST /auth/session is:

{
  "arguments": [
    0
  ],
  "backend": "string"
}

Where the actual values should look like following, in order to be usable:

    {
        "backend": "oidc",
        "arguments": {
            "access_token": access_token,
            "token_type": "Bearer",
        }
    }

All examples should be reviewed an replaced with functional values.