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-jni/widgets/WrapperWidget.c

@@ -5,6 +5,8 @@
 
 #include "../sk_area/sk_area.h"
 
+#include "../generated_headers/android_view_View.h"
+
 #include "WrapperWidget.h"
 
 G_DEFINE_TYPE(WrapperWidget, wrapper_widget, GTK_TYPE_WIDGET)
@@ -122,4 +124,10 @@ void wrapper_widget_set_jobject(WrapperWidget *wrapper, JNIEnv *env, jobject job
 		// add a callback for when the widget is mapped, which will call onMeasure to figure out what size the widget wants to be
 		g_signal_connect(wrapper, "map", G_CALLBACK(on_mapped), NULL);
 	}
+
+	jmethodID ontouchevent_method = _METHOD(_CLASS(jobj), "onTouchEvent", "(Landroid/view/MotionEvent;)Z");
+	if (ontouchevent_method != handle_cache.view.onTouchEvent) {
+		/* use gtk_widget_get_first_child since the jobject may not have the "widget" variable set yet */
+		_setOnTouchListener(env, jobj, gtk_widget_get_first_child(wrapper), NULL);
+	}
 }