Feature/policy scan

[tamim1517]

This PR adds a local policy scan script to make OPA/Rego policy testing easier for students.

Key Changes

1. Added local OPA policy scan script.
2. Supports service, resource, and policy-level scans.
3. Supports message and details output.
4. Runs existing branch name checker.
5. Runs existing GCP linter.
6. Shows scanned and skipped policy summary.

[tamim1517]

Updates:

• Supports provider-level scan.
• Supports shorthand flags for --provider, --service, --resource and --policy etc.
• Automatically generates missing plan.json files using Terraform commands.
• Separates Terraform plan.json generation from OPA policy scanning.
• Uses concurrent processing for faster Terraform generation and OPA scans.
• Adds separate worker controls for Terraform generation and OPA scanning.
• Uses 2 default workers for Terraform generation and 4 default workers for OPA scanning.
• Shows successful and failed policy scan summaries.
• Reports failed checks with clear reasons.