Revert the Metal Experiment (#701)

Metal sounded like a good idea to get in the emulator but frankly I
underestimated just how experimental and not ready it was.
From my write up in the Discord:
```
As is, Metal supports only a few games.
The games it does support freeze on first use of not playing them via Vulkan, because shader translation is broken.
So you need to use a dirty hack to not delete all your shaders.
Not to mention it breaks many games via MoltenVK because of changes to the shared GPU code.

Merging Metal seemed like a great idea, because of the few games it does support.
But I don't think it's worth it. Many of the games it breaks via MoltenVK *don't work via Metal*. 
Which effectively makes current Ryubing worse for Mac users than Ryujinx 1.1.1403.

I think what I'm gonna do is revert Metal, and reopen it as a PR. That way, you can still take advantage of the Metal backend as is, but without making other games worse with no solution.
```

For what it's worth, the shader translation part could at least be
"fixed" by always applying a 30ms delay for shader translation to Metal.
That being said, that solution sucks ass.
The MoltenVK regressions are even worse.



I hope this is not a let down to the Mac users. I hope you realize I'm
reverting this because you're actively getting a worse experience with
it in the emulator.

src/Ryujinx/UI/Windows/SettingsWindow.axaml.cs

@@ -64,34 +64,34 @@ namespace Ryujinx.Ava.UI.Windows
             {
                 switch (navItem.Tag.ToString())
                 {
-                    case nameof(UiPage):
+                    case "UiPage":
                         UiPage.ViewModel = ViewModel;
                         NavPanel.Content = UiPage;
                         break;
-                    case nameof(InputPage):
+                    case "InputPage":
                         NavPanel.Content = InputPage;
                         break;
-                    case nameof(HotkeysPage):
+                    case "HotkeysPage":
                         NavPanel.Content = HotkeysPage;
                         break;
-                    case nameof(SystemPage):
+                    case "SystemPage":
                         SystemPage.ViewModel = ViewModel;
                         NavPanel.Content = SystemPage;
                         break;
-                    case nameof(CpuPage):
+                    case "CpuPage":
                         NavPanel.Content = CpuPage;
                         break;
-                    case nameof(GraphicsPage):
+                    case "GraphicsPage":
                         NavPanel.Content = GraphicsPage;
                         break;
-                    case nameof(AudioPage):
+                    case "AudioPage":
                         NavPanel.Content = AudioPage;
                         break;
-                    case nameof(NetworkPage):
+                    case "NetworkPage":
                         NetworkPage.ViewModel = ViewModel;
                         NavPanel.Content = NetworkPage;
                         break;
-                    case nameof(LoggingPage):
+                    case "LoggingPage":
                         NavPanel.Content = LoggingPage;
                         break;
                     case nameof(HacksPage):