ClockSettings: Add a GUI application to set the system time zone

This application can be expanded with other clock-related options. For
an initial iteration, it has just an option to change the time zone.

Userland/Applications/ClockSettings/CMakeLists.txt

@@ -0,0 +1,17 @@
+serenity_component(
+    ClockSettings
+    RECOMMENDED
+    TARGETS ClockSettings
+)
+
+compile_gml(ClockSettingsWidget.gml ClockSettingsWidgetGML.h clock_settings_widget_gml)
+
+set(SOURCES
+    main.cpp
+    ClockSettingsWidget.cpp
+    ClockSettingsWidget.h
+    ClockSettingsWidgetGML.h
+)
+
+serenity_app(ClockSettings ICON app-analog-clock) # FIXME: Create a ClockSettings icon.
+target_link_libraries(ClockSettings LibGUI LibMain)