feat: helper functions for annotations, template cleanup

[golanglemonade]

• Adds defined helper functions for the entfga Annotations to make it easier to add to schemas. The struct can still directly be used.
• Cleans up and simplifies template for checks to get rid of unnecessary code that would never be hit ("e.g. "id" != "id" checks are now a template check, and not a check in the code itself.
• Adds wrapper functions to make using the generated authz checks easier to use

[sonarqubecloud]

Quality Gate failed

Failed conditions
13.2% Coverage on New Code (required ≥ 20%)

See analysis details on SonarQube Cloud