WindowServer: Implement tile window overlay

This adds a tiling mode that will show a tile window overlay rather
than immediately tiling a window, triggering window resizes.

Userland/Applications/DisplaySettings/EffectsSettings.gml

@@ -121,6 +121,22 @@
                     }
                 }
 
+                @GUI::Widget {
+                    layout: @GUI::HorizontalBoxLayout {}
+
+                    @GUI::Label {
+                        text: "Tile Window Behavior:"
+                        autosize: true
+                    }
+
+                    @GUI::Layout::Spacer {}
+
+                    @GUI::ComboBox {
+                        name: "tile_window_combobox"
+                        fixed_width: 130
+                    }
+                }
+
                 @GUI::Widget {
                     fixed_height: 4
                 }