[StepperPWM] Updated driver with latest CountedPWM implementation

CMakeLists.txt

src/shared/actuators/Stepper.h

src/shared/actuators/StepperPWM.h

src/shared/drivers/timer/CountedPWM.cpp

src/shared/drivers/timer/CountedPWM.h

src/tests/actuators/test-stepper-pwm.cpp

src/tests/actuators/test-stepper.cpp

src/tests/drivers/timer/test-counted-pwm.cpp