Sets or gets a range slider's step value.
Note: This property is only relevant when the sliderType is set to 'Stepped'.
The stepped range slider is divided into specific steps within a set range. The
handles of the slider move along the tick marks displaying each step value. The step value
represents either the size of each step, or the number of steps within the slider's set range. Use the
stepType to set the type of step that defines the step value.