Add scrollpanel widget

This PR introduces a new ScrollPanel component with the following
capabilities:
- Scroll Orientation Support: Allows scrolling in horizontal, vertical,
  or both directions, providing flexibility for different use cases.
- Partial Object Rendering: Supports partial rendering of objects that
  are only partially visible within the scroll boundaries, improving
  visual accuracy and performance.
- Boundary-Constrained Mouse Interaction: Handles mouse events strictly
  within the panel's visible boundaries, preventing interaction with
  objects outside the scrollable area.
- Minimum Internal Size (min_width, min_height): Introduces support for
  virtual space management, allowing the panel to maintain a minimum
  internal size independent of its actual on-screen dimensions. Even
  when the panel is resized, this ensures that the content respects a
  defined virtual space (with min_width and min_height), effectively
  simulating a larger internal canvas. This is particularly useful for
  large content or scenarios where a more extensive scrollable area is
  required than the current visible panel.

source/gui/Scripting/JSInterface_GUIProxy.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2024 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -23,6 +23,7 @@
 #include "gui/ObjectTypes/CButton.h"
 #include "gui/ObjectTypes/CList.h"
 #include "gui/ObjectTypes/CMiniMap.h"
+#include "gui/ObjectTypes/CScrollPanel.h"
 #include "gui/ObjectTypes/CText.h"
 
 // Called for every specialization - adds the common interface.
@@ -66,3 +67,10 @@ template<> void JSI_GUIProxy<CMiniMap>::CreateFunctions(const ScriptRequest& rq,
 	CreateFunction<&CMiniMap::Flare>(rq, cache, "flare");
 }
 DECLARE_GUIPROXY(CMiniMap);
+
+// CScrollPanel
+template<> void JSI_GUIProxy<CScrollPanel>::CreateFunctions(const ScriptRequest& rq, GUIProxyProps* cache)
+{
+	CreateFunction<&CScrollPanel::ResetScrollPosition>(rq, cache, "resetScrollPosition");
+}
+DECLARE_GUIPROXY(CScrollPanel);