api-impl{-jni}: make view.onTouchEvent work, misc stuff to make input work for Unity games

onTouchEvent was previously incorrectly handled in GLSurfaceView; move it
to View so that it works properly with any of it's descendants.

This is done by reusing the existing setOnTouchListener implementation
and changing it to use GtkEventControllerLegacy which provides motion
events.

Technically some of the code is in WrapperWidget.c since every widget
calls wrapper_widget_set_jobject and we already have related code
there.

src/api-impl/android/view/View.java

@@ -874,6 +874,10 @@ public class View extends Object {
 		this.gravity = gravity;
 	}
 
+	public boolean onTouchEvent(MotionEvent event) {
+		return true;
+	}
+
 	public native void setOnTouchListener(OnTouchListener l);
 	public native void setOnClickListener(OnClickListener l);
 	public /*native*/ void setOnSystemUiVisibilityChangeListener(OnSystemUiVisibilityChangeListener l) {}