Call Window.onFramebufferSizeChanged to resize (fixes #705)

Instead of setting the the values via accessor and calling the handler directly.
This allows mods like ResolutionControl+ to properly resize its internal
framebuffers as well.

src/main/java/com/replaymod/render/mixin/MainWindowAccessor.java

@@ -15,4 +15,6 @@ public interface MainWindowAccessor {
     int getFramebufferHeight();
     @Accessor
     void setFramebufferHeight(int value);
+    @Invoker
+    void invokeOnFramebufferSizeChanged(long window, int width, int height);
 }