Base+Playground: Add app-playground.png 16x16 and 32x32 icons

DevTools/Playground/CMakeLists.txt

@@ -2,5 +2,5 @@ set(SOURCES
     main.cpp
 )
 
-serenity_app(Playground)
+serenity_app(Playground ICON app-playground)
 target_link_libraries(Playground LibGUI)

DevTools/Playground/main.cpp

@@ -26,6 +26,7 @@
 
 #include <LibGUI/Application.h>
 #include <LibGUI/GMLSyntaxHighlighter.h>
+#include <LibGUI/Icon.h>
 #include <LibGUI/Splitter.h>
 #include <LibGUI/TextEditor.h>
 #include <LibGUI/Window.h>
@@ -33,8 +34,10 @@
 int main(int argc, char** argv)
 {
     auto app = GUI::Application::construct(argc, argv);
+    auto app_icon = GUI::Icon::default_icon("app-playground");
     auto window = GUI::Window::construct();
     window->set_title("GML Playground");
+    window->set_icon(app_icon.bitmap_for_size(16));
     window->resize(800, 600);
 
     auto& splitter = window->set_main_widget<GUI::HorizontalSplitter>();