Add support for account and entity permissions endpoints

[dawiddzhafarov]

📝 Description

This PR adds support for two new IAM endpoints:

• GET /iam/users/{username}/permissions/{entityType}/{entityId}
• GET /iam/users/{username}/permissions/account

Changes include basic unit test cases along the integration tests.

✔️ How to Test

Use DEVCLOUD linode token along the URL: https://api.devcloud.linode.com/v4beta/.
iam_beta customer tag is required.

To run unit tests:
make test-unit

To run new integration tests:

• make TEST_CASE=test_get_entity_permissions test-int
• make TEST_CASE=test_get_account_permissions test-int

Or run all IAM integration tests:
make TEST_SUITE="iam" test-int

Note that the IAM endpoints might not be stable and return random 500s.

[Copilot]

Pull request overview

This PR adds support for two new IAM endpoints that allow retrieving user permissions at both account and entity levels. The implementation includes the core API methods, unit tests with fixtures, and integration tests.

Changes:

• Added two new methods to the IAM group for retrieving account-level and entity-level permissions
• Created unit tests with JSON fixtures to validate the new methods
• Added integration tests to verify the endpoints work with live API

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
linode_api4/groups/iam.py	Implements account_permissions_get and entity_permissions_get methods for the IAM group
test/unit/groups/iam_test.py	Adds unit tests for both new permission endpoints
test/fixtures/iam_users_myusername_permissions_account.json	Fixture data for account permissions unit test
test/fixtures/iam_users_myusername_permissions_linode_1.json	Fixture data for entity permissions unit test
test/integration/models/iam/iam_test.py	Adds integration tests for both permission endpoints

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[vshanthe]

Test Passing ! LGTM