widget: Hook GTK_PHASE_TARGET controllers to the default event handlers

widget: Hook GTK_PHASE_TARGET controllers to the default event handlers

Just call the controllers on that phase if the default widget handlers
are run.

For compatibility reasons, in the touch event handler, let the pointer
emulating touch be transformed to a pointer event as usual, in order to
have widget handlers a chance to run at all. If they have to be managed
by a controller in that phase, it'll have to be through the default pointer
event handlers.