test: add new helper function for absolute events

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: add tests for checking event values

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: add tests for mt event values

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: test for trying to enable invalid abs axis

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Don't sync mt axes that don't exist

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
test: add test for abs and mt syncing

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