Move GUI size init into constructor

Setting the initial size in `Initialize` has no effect on the windows size so it's set in the constructor instead.

Content.Client/Construction/ConstructionButton.cs

@@ -1,4 +1,4 @@
-using Content.Client.GameObjects.Components.Construction;
+using Content.Client.GameObjects.Components.Construction;
 using Robust.Client.Interfaces.Graphics;
 using Robust.Client.UserInterface.Controls;
 using Robust.Shared.Maths;
@@ -41,10 +41,7 @@ namespace Content.Client.Construction
 
         private void PerformLayout()
         {
-            Menu = new ConstructionMenu(_displayManager)
-            {
-                Size = new Vector2(500.0f, 350.0f)
-            };
+            Menu = new ConstructionMenu(_displayManager);
             Menu.AddToScreen();
         }