7996: Always on Top setting does not persist (#8125)

<!-- Enter a brief description/summary of your PR here. What does it fix/what does it change/how was it tested (even manually, if necessary)? -->
## Summary of the Pull Request

<!-- Other than the issue solved, is this relevant to any other issues/existing PRs? --> 
## References

<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist
* [x] Closes https://github.com/microsoft/terminal/issues/7996
* [x] CLA signed.
* [ ] Documentation updated - irrelevant
* [ ] Schema updated - irrelevant
* [ ] 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

<!-- Provide a more detailed description of the PR, other things fixed or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments
Currently the value of AlwaysOnTop is read by the AppHost from AppLogic that takes this value from the root TerminalPage. However at this stage neither AppLogic nor TerminalPage are initialized, and thus the return value is always false.

This PR introduces a "GetInitialAlwaysOnTop" method to AppLogic that returns a value that is configured in the settings.
In addition, the TerminalPage creation was fixed to read the configuration value upon creation (and not just after settings reload).

<!-- Describe how you validated the behavior. Add automated tests wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed
* Only manual testing
* Starting the system with both initial value set to true and false
* Verifying that dynamic toggling on / off is not affected

src/cascadia/TerminalApp/AppLogic.cpp

@@ -615,6 +615,17 @@ namespace winrt::TerminalApp::implementation
         return _settings.GlobalSettings().ShowTabsInTitlebar();
     }
 
+    bool AppLogic::GetInitialAlwaysOnTop()
+    {
+        if (!_loadedInitialSettings)
+        {
+            // Load settings if we haven't already
+            LoadSettings();
+        }
+
+        return _settings.GlobalSettings().AlwaysOnTop();
+    }
+
     // Method Description:
     // - See Pane::CalcSnappedDimension
     float AppLogic::CalcSnappedDimension(const bool widthOrHeight, const float dimension) const

src/cascadia/TerminalApp/AppLogic.h

@@ -41,6 +41,7 @@ namespace winrt::TerminalApp::implementation
         winrt::Windows::UI::Xaml::ElementTheme GetRequestedTheme();
         Microsoft::Terminal::Settings::Model::LaunchMode GetLaunchMode();
         bool GetShowTabsInTitlebar();
+        bool GetInitialAlwaysOnTop();
         float CalcSnappedDimension(const bool widthOrHeight, const float dimension) const;
 
         Windows::UI::Xaml::UIElement GetRoot() noexcept;

src/cascadia/TerminalApp/AppLogic.idl

@@ -47,6 +47,7 @@ namespace TerminalApp
         Windows.UI.Xaml.ElementTheme GetRequestedTheme();
         Microsoft.Terminal.Settings.Model.LaunchMode GetLaunchMode();
         Boolean GetShowTabsInTitlebar();
+        Boolean GetInitialAlwaysOnTop();
         Single CalcSnappedDimension(Boolean widthOrHeight, Single dimension);
         void TitlebarClicked();
         void WindowCloseButtonClicked();

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -239,6 +239,8 @@ namespace winrt::TerminalApp::implementation
         //
         // _OnFirstLayout will remove this handler so it doesn't get called more than once.
         _layoutUpdatedRevoker = _tabContent.LayoutUpdated(winrt::auto_revoke, { this, &TerminalPage::_OnFirstLayout });
+
+        _isAlwaysOnTop = _settings.GlobalSettings().AlwaysOnTop();
     }
 
     // Method Description:

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -58,7 +58,7 @@ AppHost::AppHost() noexcept :
                                                 std::placeholders::_1,
                                                 std::placeholders::_2));
     _window->MouseScrolled({ this, &AppHost::_WindowMouseWheeled });
-    _window->SetAlwaysOnTop(_logic.AlwaysOnTop());
+    _window->SetAlwaysOnTop(_logic.GetInitialAlwaysOnTop());
     _window->MakeWindow();
 }