CmdPal: Light, dark, pink, and unicorns (#43505)

<!-- 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

This PR introduces user settings for app mode themes (dark, light, or
system) and background customization options, including custom colors,
system accent colors, or custom images.

- Adds a new page to the Settings window with new appearance settings
and moves some existing settings there as well.
- Introduces a new core-level service abstraction, `IThemeService`, that
holds the state for the current theme.
- Uses the helper class `ResourceSwapper` to update application-level
XAML resources. The way WinUI / XAML handles these is painful, and XAML
Hot Reload is pain². Initialization must be lazy, as XAML resources can
only be accessed after the window is activated.
- `ThemeService` takes app and system settings and selects one of the
registered `IThemeProvider`s to calculate visuals and choose the
appropriate XAML resources.
  - At the moment, there are two:
    - `NormalThemeProvider`
      - Provides the current uncolorized light and dark styles  
      - `ms-appx:///Styles/Theme.Normal.xaml`
    - `ColorfulThemeProvider`
- Style that matches the Windows 11 visual style (based on the Start
menu) and colors
      - `ms-appx:///Styles/Theme.Colorful.xaml`  
- Applied when the background is colorized or a background image is
selected
- The app theme is applied only on the main window
(`WindowThemeSynchronizer` helper class can be used to synchronize other
windows if needed).
- Adds a new dependency on `Microsoft.Graphics.Win2D`.
- Adds a custom color picker popup; the one from the Community Toolkit
occasionally loses the selected color.
- Flyby: separates the keyword tag and localizable label for pages in
the Settings window navigation.


## Pictures? Pictures!

<img width="2027" height="1276" alt="image"
src="https://github.com/user-attachments/assets/e3485c71-7faa-495b-b455-b313ea6046ee"
/>

<img width="3776" height="2025" alt="image"
src="https://github.com/user-attachments/assets/820fa823-34d4-426d-b066-b1049dc3266f"
/>

Matching Windows accent color and tint:

<img width="3840" height="2160" alt="image"
src="https://github.com/user-attachments/assets/65f3b608-e282-4894-b7c8-e014a194f11f"
/>


<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

- [x] Closes: #38444
- [ ] **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

<!-- 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

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

---------

Co-authored-by: Niels Laute <[email protected]>

Author: jiripolasek

.github/actions/spell-check/expect.txt

@@ -141,6 +141,7 @@ BITSPIXEL
 bla
 BLACKFRAME
 BLENDFUNCTION
+blittable
 Blockquotes
 blt
 BLURBEHIND
@@ -250,6 +251,7 @@ colorformat
 colorhistory
 colorhistorylimit
 COLORKEY
+colorref
 comctl
 comdlg
 comexp
@@ -1860,8 +1862,10 @@ Uniquifies
 unitconverter
 unittests
 UNLEN
+Uninitializes
 UNORM
 unremapped
+Unsubscribes
 unvirtualized
 unwide
 unzoom

Directory.Packages.props

@@ -40,6 +40,7 @@
     <PackageVersion Include="Microsoft.Data.Sqlite" Version="9.0.10" />
     <!-- Including Microsoft.Bcl.AsyncInterfaces to force version, since it's used by Microsoft.SemanticKernel. -->
     <PackageVersion Include="Microsoft.Bcl.AsyncInterfaces" Version="9.0.10" />
+    <PackageVersion Include="Microsoft.Graphics.Win2D" Version="1.3.2" />
     <PackageVersion Include="Microsoft.Windows.CppWinRT" Version="2.0.240111.5" />
     <PackageVersion Include="Microsoft.Diagnostics.Tracing.TraceEvent" Version="3.1.16" />
     <PackageVersion Include="Microsoft.Extensions.AI" Version="9.9.1" />

src/common/ManagedCsWin32/CLSID.cs

@@ -16,4 +16,5 @@ public static partial class CLSID
     public static readonly Guid CollatorDataSource = new Guid("9E175B8B-F52A-11D8-B9A5-505054503030");
     public static readonly Guid ApplicationActivationManager = new Guid("45BA127D-10A8-46EA-8AB7-56EA9078943C");
     public static readonly Guid VirtualDesktopManager = new("aa509086-5ca9-4c25-8f95-589d3c07b48a");
+    public static readonly Guid DesktopWallpaper = new("C2CF3110-460E-4FC1-B9D0-8A1C0C9CC4BD");
 }

src/common/ManagedCsWin32/Ole32.cs

@@ -16,6 +16,12 @@ public static partial int CoCreateInstance(
         CLSCTX dwClsContext,
         ref Guid riid,
         out IntPtr rReturnedComObject);
+
+    [LibraryImport("ole32.dll")]
+    internal static partial int CoInitializeEx(nint pvReserved, uint dwCoInit);
+
+    [LibraryImport("ole32.dll")]
+    internal static partial void CoUninitialize();
 }
 
 [Flags]

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/ShellViewModel.cs

@@ -14,6 +14,7 @@
 namespace Microsoft.CmdPal.Core.ViewModels;
 
 public partial class ShellViewModel : ObservableObject,
+    IDisposable,
     IRecipient<PerformCommandMessage>,
     IRecipient<HandleCommandResultMessage>
 {
@@ -460,4 +461,12 @@ public void CancelNavigation()
     {
         _navigationCts?.Cancel();
     }
+
+    public void Dispose()
+    {
+        _handleInvokeTask?.Dispose();
+        _navigationCts?.Dispose();
+
+        GC.SuppressFinalize(this);
+    }
 }