Expose certain PP5 context properties in PP5EnrollTransform

@JordanCheney @mmtaborsky While the default PP5 settings are good for getting the maximum recognition performance under all conditions, they are non-ideal when enrollment speed is a concern. This PR allows certain context properties to be set in the algorithm string that are particularly relevant for changing the speed/accuracy tradeoff.
That is a fair point. Perhaps just a comment then explaining that it the value is not number of pixels or something