test: fix MockSensor do_command state tracking and add missing coverage

[luckys00]

What this PR does

Fixes an inconsistency in the MockSensor class where do_command was dropping state parameters (timeout and extra), and adds the missing test coverage for do_command across the Sensor, Service, and Client test suites.

Why is it needed?

While get_readings and get_geometries properly save self.extra and self.timeout to the mock's state, the do_command implementation was bypassing this and simply returning the command. This makes it impossible to assert if custom commands with timeouts were actually processed correctly by the mock.

Additionally, this PR adds proper test coverage for do_command in test_sensor.py to ensure the timeout parameter successfully travels through the gRPC channel.

Changes Made:

• Updated do_command in tests/mocks/components.py to properly track self.timeout and self.extra.
• Added missing do_command tests in TestSensor, TestService, and TestClient (asserting timeout state logic while acknowledging gRPC drops extra for this specific request).

[viambot]

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[njooma]

Hi! Thanks for contributing! We are actually in the process of updating all our tests. If you want to take a look at how the test_camera.py tests are now implemented, we are moving towards that for all our resources.

If you like, you can update the sensor tests to use that framework!

[luckys00]

Thanks for the review and the heads-up, @njooma ! It's great to hear about the new testing framework. I'll take a look at how test_camera.py is implemented and update the do_command tests for the Sensor components to match that new structure. Will push the changes shortly!