highlightMoveSpeed should be time of transition - not speed per pixel - to prevent resolution-dependant behavior

Using speed as highlightMoveSpeed is detrimental to the user experience - as the UX will depend on the resolution. Basically, if a QML UI is written to be dynamic depending on the toplevel size - the animation will appear to move much faster at a lower resolution. Instead of highlightMoveSpeed it should use highlightMoveDuration - to mirror the API of Transition