ports/psoc6: Adding code for machine.Signal functionality.

[NikhitaR-IFX]

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Description

• Enables Signal module and available functions work.
• Ideally, I would have wanted to reuse the APIs in driver but hal apis were more promising.
• The tests/extmod/machine_signal.py should be passed but there are two problems:

1. It depends on machine.PinBase which is another extmod extended by MPY but needs to enabled in our port.
2. The value() is not used as it is mentioned here. The guide says value() returns undefined value which is how we implement in our por,t but the tests by mpy assume they return the digital value on that pin. Hence this test might not be useful even if we enable it.