test: move synaptics-specific parts out

Split the synaptics-specifics out into a separate file so we can load up the
test-suite with other devices.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: make test movements relative to the touchpad size

Instead of specifying the coordinates on the touchpad, specify a range of
0-100% and translate that into device-specific movements.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>