since the keycode for a tap dance process gets process only after the
TAPPING_TERM timeout, you really only have ONESHOT_TIMEOUT -
TAPPING_TERM time to tap or double tap on the key. This fix save the
oneshot_mods into the action.state structure and applies the mods with
the keycode when it's registered. It also unregisters the mod when the
the tap dance process gets reset.