Oldchat (#11913)

* attempt at moving MainViewport to UIWidget

* oldchat (prototype)

* separate oldchat and default ss14 HUD into their own files

* restores original default game screen logic and adds that logic into separated chat game screen

* hand reloading, several tweaks to port oldchat to main ss14 branch

oldchat is currently not selectable

* screen type cvar, gameplay state screen reloading/loading

* reload screen on ui layout cvar change

* fixes up basic reloading (HUD switching is still very bad)

* some UI widget reloading for main UI screen switching

* alert sync on screen change

* inventory reload

* hotbar margin fix

* chat bubbles above viewport

* whoops

* fixes ordering of speech bubble root

* should fix the chat focus issue (at least in-game, not lobby yet)

* should fix up the lobby/game chat focus

* fixes chat for lobby, turns lobby into a UI state

* viewport UI controller

* viewport ratio selection

* whoops

* adds the /tg/ widescreen ratio

* removes warning from inventory UI controller, adds background to separated chat game screen's chat portion

* menu button reload

* unload menu buttons only from gameplay state shutdown

* bugfix

* character button fix

* adds config options for viewport width/UI layout

* variable naming changes, get or null instead of get to avoid exceptions

* moves entity system get into controller

Content.Client/UserInterface/Controls/MainViewport.cs

@@ -1,6 +1,7 @@
 using Content.Client.Viewport;
 using Content.Shared.CCVar;
 using Robust.Client.UserInterface;
+using Robust.Client.UserInterface.Controls;
 using Robust.Shared.Configuration;
 
 namespace Content.Client.UserInterface.Controls
@@ -9,7 +10,7 @@ namespace Content.Client.UserInterface.Controls
     ///     Wrapper for <see cref="ScalingViewport"/> that listens to configuration variables.
     ///     Also does NN-snapping within tolerances.
     /// </summary>
-    public sealed class MainViewport : Control
+    public sealed class MainViewport : UIWidget
     {
         [Dependency] private readonly IConfigurationManager _cfg = default!;
         [Dependency] private readonly ViewportManager _vpManager = default!;