OPA Policy for IAM Role Tagging

I need an OPA policy that enforces mandatory tagging for IAM roles. The policy should be written in Rego language and integrate with our existing OPA setup.

Ideal skills and experience:
- Proficiency in Rego language
- Experience with OPA and IAM policies
- Familiarity with cloud providers (AWS, Azure, Google Cloud)
- Ability to integrate new policies into existing OPA setups