ecore/wayland: Send a mouse up event when the implicit grab starts.

ecore/wayland: Send a mouse up event when the implicit grab starts.

The previous workaround used to send a mouse up event to the
application, using the pointer enter callback to determine when an
implicit grab has finished. This was "simulating" a mouse up event when
the surface move or resize finished.

However, this doesn't work for touch-based move. The pointer enter isn't
emitted, because the wl_touch interface doesn't have the concept of a
pointer.

Changing this code to make it more similar to what Weston's toytoolkit
does, the mouse up event is sent as soon as the move or resize grab
starts. After that, the compositor takes care of the move/resize almost
entirely.

Should fix T468.