Integrations for IAM role-permissions and Entities

[vshanthe]

📝 Description

Test Against Devcloud using API TOKEN
and URL - https://api.devcloud.linode.com/v4beta/

✔️ How to Test

make test-int TEST_CASE=iam_test.py

📷 Preview

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[Copilot]

Pull Request Overview

Adds new integration tests for IAM role permissions retrieval, user-specific permissions, and entity listing, with a skipped test for updating user role permissions.

• Introduces tests for global and user IAM role permissions.
• Adds entity listing validation.
• Includes (but skips) a test for setting user role permissions.

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