Remove some BUI boilerplate (#28399)

* Remove some BUI boilerplate

- The disposals overrides got removed due to the helper method handling it.
- Replace window creation with CreateWindow helper.
- Fixed some stinky code which would cause exceptions.

* More

* moar

* weh

* done

* More BUIs

* More updates

* weh

* moar

* look who it is

* weh

* merge

* weh

* fixes

Content.Client/Paper/UI/PaperWindow.xaml.cs

@@ -17,6 +17,7 @@ namespace Content.Client.Paper.UI
     public sealed partial class PaperWindow : BaseWindow
     {
         [Dependency] private readonly IInputManager _inputManager = default!;
+        [Dependency] private readonly IResourceCache _resCache = default!;
 
         private static Color DefaultTextColor = new(25, 25, 25);
 
@@ -85,11 +86,10 @@ namespace Content.Client.Paper.UI
             // Randomize the placement of any stamps based on the entity UID
             // so that there's some variety in different papers.
             StampDisplay.PlacementSeed = (int)entity;
-            var resCache = IoCManager.Resolve<IResourceCache>();
 
             // Initialize the background:
             PaperBackground.ModulateSelfOverride = visuals.BackgroundModulate;
-            var backgroundImage = visuals.BackgroundImagePath != null? resCache.GetResource<TextureResource>(visuals.BackgroundImagePath) : null;
+            var backgroundImage = visuals.BackgroundImagePath != null? _resCache.GetResource<TextureResource>(visuals.BackgroundImagePath) : null;
             if (backgroundImage != null)
             {
                 var backgroundImageMode = visuals.BackgroundImageTile ? StyleBoxTexture.StretchMode.Tile : StyleBoxTexture.StretchMode.Stretch;
@@ -127,7 +127,7 @@ namespace Content.Client.Paper.UI
             PaperContent.ModulateSelfOverride = visuals.ContentImageModulate;
             WrittenTextLabel.ModulateSelfOverride = visuals.FontAccentColor;
 
-            var contentImage = visuals.ContentImagePath != null ? resCache.GetResource<TextureResource>(visuals.ContentImagePath) : null;
+            var contentImage = visuals.ContentImagePath != null ? _resCache.GetResource<TextureResource>(visuals.ContentImagePath) : null;
             if (contentImage != null)
             {
                 // Setup the paper content texture, but keep a reference to it, as we can't set