Move/Rename stuff (#11209)

-     Change namespace, and folder of FancyWindow to Content.Client.UserInterface.Controls
-     Change xaml reference from ui to controls in some places
-     Change ClientAlertsSystem from internal to public
-     Change namespace, and folder of HighDivider to Content.Client.UserInterface.Controls

Content.Client/Hands/HandsComponent.cs

@@ -1,3 +1,5 @@
+using Content.Client.Hands.Systems;
+using Content.Client.Hands.UI;
 using Content.Shared.Hands.Components;
 
 namespace Content.Client.Hands

Content.Client/Hands/ShowHandItemOverlay.cs

@@ -1,3 +1,4 @@
+using Content.Client.Hands.Systems;
 using Content.Shared.CCVar;
 using Robust.Client.GameObjects;
 using Robust.Client.Graphics;

Content.Client/Hands/Systems/HandVirtualItemSystem.cs

@@ -1,4 +1,5 @@
-using Content.Client.Items;
+using Content.Client.Hands.UI;
+using Content.Client.Items;
 using Content.Shared.Hands;
 using Content.Shared.Hands.Components;
 using JetBrains.Annotations;

Content.Client/Hands/Systems/HandsSystem.cs

@@ -1,6 +1,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Content.Client.Animations;
+using Content.Client.Hands.UI;
 using Content.Client.HUD;
 using Content.Shared.Hands;
 using Content.Shared.Hands.Components;
@@ -14,7 +15,7 @@ using Robust.Shared.GameStates;
 using Robust.Shared.Map;
 using Robust.Shared.Timing;
 
-namespace Content.Client.Hands
+namespace Content.Client.Hands.Systems
 {
     [UsedImplicitly]
     public sealed class HandsSystem : SharedHandsSystem

Content.Client/Hands/UI/HandVirtualItemStatus.xaml.cs

@@ -1,7 +1,7 @@
 using Robust.Client.UserInterface;
 using Robust.Client.UserInterface.XAML;
 
-namespace Content.Client.Hands
+namespace Content.Client.Hands.UI
 {
     public sealed class HandVirtualItemStatus : Control
     {

Content.Client/Hands/UI/HandsGui.xaml.cs

@@ -1,6 +1,5 @@
-using System;
-using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using Content.Client.Hands.Systems;
 using Content.Client.HUD;
 using Content.Client.Inventory;
 using Content.Client.Items.Managers;
@@ -14,13 +13,10 @@ using Robust.Client.ResourceManagement;
 using Robust.Client.UserInterface;
 using Robust.Client.UserInterface.XAML;
 using Robust.Shared.Configuration;
-using Robust.Shared.GameObjects;
 using Robust.Shared.Input;
-using Robust.Shared.IoC;
 using Robust.Shared.Timing;
-using Robust.Shared.ViewVariables;
 
-namespace Content.Client.Hands
+namespace Content.Client.Hands.UI
 {
     [GenerateTypedNameReferences]
     public sealed partial class HandsGui : Control