New Druid OPA authorizer 0.6.0

[fhennig]

There is a new OPA authorizer with breaking API changes: https://github.com/stackabletech/druid-opa-authorizer/releases/tag/0.6.0

• build the new authorizer with the release action to create github artifacts
• update the Dockerfile to pull in the new 0.6.0 version
• Update documentation to reflect the new API object
• Update integration tests (they will likely break with 0.6.0)

[razvan]

Please wait with merging this.