[Settings] Optimizing and cleaning up code (#44721)

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fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request

- Removing dead experiments code
- Refactoring and simplifying OOBE/SCOOBE windowing code
- Removing dead assets
- Optimizing CmdPal assets to lower res shaving off a few MBs
- Scrolling works better on the What's new page
- Should be merged after: #44638

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## PR Checklist

- [X] Closes: #44958
<!-- - [ ] Closes: #yyy (add separate lines for additional resolved
issues) -->
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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---------

Co-authored-by: Gordon Lam (SH) <yeelam@microsoft.com>

src/settings-ui/Settings.UI/SettingsXAML/OOBE/Views/OobeFileLocksmith.xaml.cs

@@ -10,9 +10,6 @@ using Microsoft.UI.Xaml.Navigation;
 
 namespace Microsoft.PowerToys.Settings.UI.OOBE.Views
 {
-    /// <summary>
-    /// An empty page that can be used on its own or navigated to within a Frame.
-    /// </summary>
     public sealed partial class OobeFileLocksmith : Page
     {
         public OobePowerToysModule ViewModel { get; set; }
@@ -20,15 +17,15 @@ namespace Microsoft.PowerToys.Settings.UI.OOBE.Views
         public OobeFileLocksmith()
         {
             this.InitializeComponent();
-            ViewModel = new OobePowerToysModule(OobeShellPage.OobeShellHandler.Modules[(int)PowerToysModules.FileLocksmith]);
+            ViewModel = App.OobeShellViewModel.GetModule(PowerToysModules.FileLocksmith);
             DataContext = ViewModel;
         }
 
         private void SettingsLaunchButton_Click(object sender, Microsoft.UI.Xaml.RoutedEventArgs e)
         {
-            if (OobeShellPage.OpenMainWindowCallback != null)
+            if (OobeWindow.OpenMainWindowCallback != null)
             {
-                OobeShellPage.OpenMainWindowCallback(typeof(FileLocksmithPage));
+                OobeWindow.OpenMainWindowCallback(typeof(FileLocksmithPage));
             }
 
             ViewModel.LogOpeningSettingsEvent();