add robust unit test for MIoTNetwork async monitoring

[Imadnajam]

Pull Request: Add asynchronous unit test for MIoTNetwork monitoring

Added

• Event handlers for network_status and network_info changes, ensuring proper logging and validation of state transitions.

Improved

• Resource safety by using a try-finally block to guarantee cleanup with deinit_async.
• Readability with descriptive handler names and structured inline comments.

Ensured

• Clear and consistent test output by logging network state transitions during the 3-second monitoring window.

This implementation enhances the robustness and maintainability of the test, providing a strong foundation for validating MIoTNetwork's asynchronous behavior.

[SusanPhevos]

validate-lint action failed. Please correct it.