Send wl_pointer.frame when emulating pointer events out of touch ones

When touching a surface that doesn't register to wl_touch events, KWin
didn't send frame events (which it does for regular pointer and touch
events), causing severe updating issues with some clients.

Test Plan:
Launch a client that doesn't attach to wl_touch (for instance,
rootston) with WAYLAND_DEBUG=client and watch the logs while touching
its window.