WindowServer: Add Vertically/HorizontallyMaximized WindowTileTypes

VerticallyMaximized tiling replaces set_vertically_maximized() to
take advantage of tiling ergonomics.

Middle-clicking a window's maximize button now tiles vertically;
secondary-clicking tiles horizontally.

Adds Super+Alt+Arrow shortcuts for both. Super+Left/Right tiling
shortcuts now let windows shift between tile types directly.

Userland/Services/WindowServer/Window.h

@@ -48,7 +48,9 @@ enum class WindowTileType {
     TopLeft,
     TopRight,
     BottomLeft,
-    BottomRight
+    BottomRight,
+    VerticallyMaximized,
+    HorizontallyMaximized,
 };
 
 enum class WindowMenuAction {
@@ -111,8 +113,6 @@ public:
     bool is_always_on_top() const { return m_always_on_top; }
     void set_always_on_top(bool);
 
-    void set_vertically_maximized();
-
     bool is_fullscreen() const { return m_fullscreen; }
     void set_fullscreen(bool);