Base: Create /res/icons/serenity for misc. sized system icons

DevTools/VisualBuilder/main.cpp

@@ -168,7 +168,7 @@ RefPtr<GUI::Window> make_toolbox_window()
     auto& radiobutton_button = widget.add<GUI::Button>();
     radiobutton_button.set_button_style(Gfx::ButtonStyle::CoolBar);
     radiobutton_button.set_tooltip("GRadioButton");
-    radiobutton_button.set_icon(Gfx::Bitmap::load_from_file("/res/icons/filled-radio-circle.png"));
+    radiobutton_button.set_icon(Gfx::Bitmap::load_from_file("/res/icons/serenity/filled-radio-circle.png"));
     radiobutton_button.on_click = [](auto) {
         if (auto* form = VBForm::current())
             form->insert_widget(VBWidgetType::GRadioButton);

Libraries/LibGUI/TreeView.cpp

@@ -58,8 +58,8 @@ TreeView::TreeView()
     set_background_role(ColorRole::Base);
     set_foreground_role(ColorRole::BaseText);
     set_column_headers_visible(false);
-    m_expand_bitmap = Gfx::Bitmap::load_from_file("/res/icons/treeview-expand.png");
-    m_collapse_bitmap = Gfx::Bitmap::load_from_file("/res/icons/treeview-collapse.png");
+    m_expand_bitmap = Gfx::Bitmap::load_from_file("/res/icons/serenity/treeview-expand.png");
+    m_collapse_bitmap = Gfx::Bitmap::load_from_file("/res/icons/serenity/treeview-collapse.png");
 }
 
 TreeView::~TreeView()

Libraries/LibGfx/ClassicStylePainter.cpp

@@ -336,10 +336,10 @@ static const Gfx::Bitmap& circle_bitmap(bool checked, bool changing)
 void ClassicStylePainter::paint_radio_button(Painter& painter, const IntRect& rect, const Palette&, bool is_checked, bool is_being_pressed)
 {
     if (!s_unfilled_circle_bitmap) {
-        s_unfilled_circle_bitmap = Bitmap::load_from_file("/res/icons/unfilled-radio-circle.png");
-        s_filled_circle_bitmap = Bitmap::load_from_file("/res/icons/filled-radio-circle.png");
-        s_changing_filled_circle_bitmap = Bitmap::load_from_file("/res/icons/changing-filled-radio-circle.png");
-        s_changing_unfilled_circle_bitmap = Bitmap::load_from_file("/res/icons/changing-unfilled-radio-circle.png");
+        s_unfilled_circle_bitmap = Bitmap::load_from_file("/res/icons/serenity/unfilled-radio-circle.png");
+        s_filled_circle_bitmap = Bitmap::load_from_file("/res/icons/serenity/filled-radio-circle.png");
+        s_changing_filled_circle_bitmap = Bitmap::load_from_file("/res/icons/serenity/changing-filled-radio-circle.png");
+        s_changing_unfilled_circle_bitmap = Bitmap::load_from_file("/res/icons/serenity/changing-unfilled-radio-circle.png");
     }
 
     auto& bitmap = circle_bitmap(is_checked, is_being_pressed);