feat(gcp): connect GCP IAM Roles to Organizations and Projects

[kunaals]

Summary

This PR adds support for IAM roles in GCP, allowing Cartography to sync and track custom roles at both project and organization levels. Key changes:

• Add organization-level IAM role syncing in GCP module
• Introduce ParentType enum to better handle project vs org-level resources
• Update schema to better represent role hierarchies and scopes
• Improve logging and error handling
• Remove unnecessary GCPPrincipal label from GSuite nodes

Related issues or links: https://github.com/cartography-cncf/cartography/issues/415

Checklist

• [x] Updated integration tests for GCP IAM module
• [x] Updated schema documentation in docs/root/modules/gcp/schema.md
• [x] Added new test data in tests/data/gcp/iam.py
• [x] Added new test cases in tests/integration/cartography/intel/gcp/test_iam.py

Resulting Graph View