Manually set the automation name of the default color scheme for scre…

…en reader (#14704)

## Summary of the Pull Request
When we navigate to the color schemes page, find the default color scheme (if present) and manually set the container's automation name to include the word 'default'. 

Note that we don't want to change the actual `ColorSchemeViewModel`'s name since that name is used internally to identify schemes. We only want to change the `ListViewItem`'s name, i.e. the container in the SUI.

## PR Checklist
* [x] Closes #14401 
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [x] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

## Validation Steps Performed
Screen reader reads out the 'default' text now. It also correctly reads out the new default scheme if the default scheme is changed via SUI or json.

src/cascadia/TerminalSettingsEditor/ColorSchemes.cpp

@@ -37,6 +37,21 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
     {
         _ViewModel = e.Parameter().as<Editor::ColorSchemesPageViewModel>();
         _ViewModel.CurrentPage(ColorSchemesSubPage::Base);
+
+        _layoutUpdatedRevoker = LayoutUpdated(winrt::auto_revoke, [this](auto /*s*/, auto /*e*/) {
+            // Only let this succeed once.
+            _layoutUpdatedRevoker.revoke();
+
+            for (const auto scheme : _ViewModel.AllColorSchemes())
+            {
+                if (scheme.IsDefaultScheme())
+                {
+                    winrt::hstring newName{ fmt::format(L"{} ({})", scheme.Name(), RS_(L"ColorScheme_DefaultTag/Text")) };
+                    Automation::AutomationProperties::SetName(ColorSchemeListView().ContainerFromItem(scheme), newName);
+                    break;
+                }
+            }
+        });
     }
 
     void ColorSchemes::AddNew_Click(const IInspectable& /*sender*/, const RoutedEventArgs& /*e*/)

src/cascadia/TerminalSettingsEditor/ColorSchemes.h

@@ -13,6 +13,7 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
 {
     struct ColorSchemes : public HasScrollViewer<ColorSchemes>, ColorSchemesT<ColorSchemes>
     {
+    public:
         ColorSchemes();
 
         void OnNavigatedTo(const winrt::Windows::UI::Xaml::Navigation::NavigationEventArgs& e);
@@ -25,6 +26,9 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         WINRT_OBSERVABLE_PROPERTY(Editor::ColorSchemesPageViewModel, ViewModel, _PropertyChangedHandlers, nullptr);
 
         WINRT_CALLBACK(PropertyChanged, Windows::UI::Xaml::Data::PropertyChangedEventHandler);
+
+    private:
+        winrt::Windows::UI::Xaml::FrameworkElement::LayoutUpdated_revoker _layoutUpdatedRevoker;
     };
 }