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/ClockSettingsWidget.gml

@@ -0,0 +1,40 @@
+@GUI::Frame {
+    fill_with_background_color: true
+
+    layout: @GUI::VerticalBoxLayout {
+        margins: [10]
+        spacing: 5
+    }
+
+    @GUI::GroupBox {
+        title: "Time Zone Settings"
+        fixed_height: 120
+
+        layout: @GUI::VerticalBoxLayout {
+            margins: [16, 8, 8]
+            spacing: 16
+        }
+
+        @GUI::Label {
+            text: "Change the system's time zone used for the clock and other applications."
+            text_alignment: "TopLeft"
+        }
+
+        @GUI::Widget {
+            layout: @GUI::HorizontalBoxLayout {
+                spacing: 4
+            }
+
+            @GUI::Label {
+                text: "Time Zone:"
+                fixed_width: 80
+                name: "time_zone_label"
+                text_alignment: "CenterLeft"
+            }
+
+            @GUI::ComboBox {
+                name: "time_zone_input"
+            }
+        }
+    }
+}