backends/native/seat-impl: Translate touch coords before storing

For the coordinates of pointers or stylii, we translate the ones we store using the viewport matrix already. For touch events otoh, we store coords untranslated and translate them later only for event emission.

Let's be consistent here and store the coordinates of touch events translated, just like we do for pointer events.

This fixes touch window dragging on rotated monitors. MetaWindowDrag calls clutter_seat_query_state(), which uses those stored coordinates. So in case of a touch sequence the coords returned by query_state() would be untranslated.