Plugin-registerable self tests

The goal of this change is to let plugins register their own self-tests. 

We do this through the `ISelfTestRegistry` interface. For a plugin it
would look like this:

```csharp
[PluginService]
public ISelfTestRegistry SelfTestRegistry

// Somewhere that gets called by your plugin
SelfTestRegistry.RegisterTestSteps([
  new MySelfTestStep(),
  new MyOtherSelfTestStep()
])
```

Where `MySelfTest` and `MyOtherSelfTest` are instances of
the existing `ISelfTestStep` interface.

The biggest changes are to `SelfTestWindow` and the introduction of
`SelfTestWithResults`. I wanted to make sure test state wasn't lost when
changing the dropdown state and I was finding it a bit annoying to work
with the Dictionary now that we can't just rely on the index of the
item.

To fix this I moved all the "test run" state into `SelfTestWithResults`,
most of the changes to `SelfTestWindow` are derived from that, other
then the addition of the combo box.

The documentation for this service is a bit sparse, but I wanted to put
it up for review first before I invest a bunch of time making nice
documentation. 

I'm keen to hear if we think this is useful or if any changes are
needed.

Dalamud/Interface/Internal/Windows/SelfTest/Steps/DalamudSelfTest.cs

@@ -0,0 +1,51 @@
+using Dalamud.Plugin.SelfTest.Internal;
+using Lumina.Excel.Sheets;
+
+namespace Dalamud.Interface.Internal.Windows.SelfTest.Steps;
+
+/// <summary>
+/// Class handling Dalamud self-test registration.
+/// </summary>
+[ServiceManager.EarlyLoadedService]
+internal class DalamudSelfTest : IServiceType
+{
+    [ServiceManager.ServiceConstructor]
+    private DalamudSelfTest(SelfTestRegistry registry)
+    {
+        registry.RegisterDalamudSelfTestSteps([
+            new LoginEventSelfTestStep(),
+            new WaitFramesSelfTestStep(1000),
+            new FrameworkTaskSchedulerSelfTestStep(),
+            new EnterTerritorySelfTestStep(148, "Central Shroud"),
+            new ItemPayloadSelfTestStep(),
+            new ContextMenuSelfTestStep(),
+            new NamePlateSelfTestStep(),
+            new ActorTableSelfTestStep(),
+            new FateTableSelfTestStep(),
+            new AetheryteListSelfTestStep(),
+            new ConditionSelfTestStep(),
+            new ToastSelfTestStep(),
+            new TargetSelfTestStep(),
+            new KeyStateSelfTestStep(),
+            new GamepadStateSelfTestStep(),
+            new ChatSelfTestStep(),
+            new HoverSelfTestStep(),
+            new LuminaSelfTestStep<Item>(true),
+            new LuminaSelfTestStep<Level>(true),
+            new LuminaSelfTestStep<Lumina.Excel.Sheets.Action>(true),
+            new LuminaSelfTestStep<Quest>(true),
+            new LuminaSelfTestStep<TerritoryType>(false),
+            new AddonLifecycleSelfTestStep(),
+            new PartyFinderSelfTestStep(),
+            new HandledExceptionSelfTestStep(),
+            new DutyStateSelfTestStep(),
+            new GameConfigSelfTestStep(),
+            new MarketBoardSelfTestStep(),
+            new SheetRedirectResolverSelfTestStep(),
+            new NounProcessorSelfTestStep(),
+            new SeStringEvaluatorSelfTestStep(),
+            new CompletionSelfTestStep(),
+            new LogoutEventSelfTestStep()
+        ]);
+    }
+}