litest: Add a sleep_ms parameter to litest_touch_move_to

litest: Add a sleep_ms parameter to litest_touch_move_to

In reality moving a touch from point to another takes time. In some cases
(when a timeout may trigger during the move, e.g. tap-n-drag on a touchpad),
this is important. Add a sleep_ms parameter, which will cause
litest_touch_move_to to sleep the specified amount of ms every step.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>