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/Mech/Ui/MechBoundUserInterface.cs

@@ -3,6 +3,7 @@ using Content.Shared.Mech;
 using Content.Shared.Mech.Components;
 using JetBrains.Annotations;
 using Robust.Client.GameObjects;
+using Robust.Client.UserInterface;
 
 namespace Content.Client.Mech.Ui;
 
@@ -20,9 +21,8 @@ public sealed class MechBoundUserInterface : BoundUserInterface
     {
         base.Open();
 
-        _menu = new(Owner);
-
-        _menu.OnClose += Close;
+        _menu = this.CreateWindow<MechMenu>();
+        _menu.SetEntity(Owner);
         _menu.OpenCenteredLeft();
 
         _menu.OnRemoveButtonPressed += uid =>
@@ -60,16 +60,6 @@ public sealed class MechBoundUserInterface : BoundUserInterface
         }
     }
 
-    protected override void Dispose(bool disposing)
-    {
-        base.Dispose(disposing);
-
-        if (!disposing)
-            return;
-
-        _menu?.Close();
-    }
-
     public UIFragment? GetEquipmentUi(EntityUid? uid)
     {
         var component = EntMan.GetComponentOrNull<UIFragmentComponent>(uid);