Remove all explicit dependencies from the toolkit and extensions api on WinAppSDK (#41261)

<!-- 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)?
-->
This pull request removes the dependencies from the toolkit and the SDK
on WinAppSDK and WebView2. This allows clients of these APIs to have
their own version dependencies.

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

- [ X] Closes: #41235 
- [ X] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ X] **Tests:** Added/updated and all pass
- [ X] **Localization:** All end-user-facing strings can be localized
- [ X] **Dev docs:** Added/updated
- [ X] **New binaries:** Added on the required places
- [ X] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ X] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ X] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ X] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ X] **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

Co-authored-by: Ross Luengen <rossl@microsoft.com>

src/modules/cmdpal/extensionsdk/Microsoft.CommandPalette.Extensions.Toolkit/Microsoft.CommandPalette.Extensions.Toolkit.csproj

@@ -41,8 +41,6 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="Microsoft.WindowsAppSDK" />
-    <PackageReference Include="Microsoft.Web.WebView2" />
     <PackageReference Include="System.Drawing.Common" />
     <!-- This line forces the WebView2 version used by Windows App SDK to be the one we expect from Directory.Packages.props . -->
   </ItemGroup>

src/modules/cmdpal/extensionsdk/Microsoft.CommandPalette.Extensions/Microsoft.CommandPalette.Extensions.vcxproj

@@ -180,4 +180,4 @@
     <Error Condition="!Exists('$(WasdkNuget)\build\native\Microsoft.WindowsAppSDK.targets')" Text="$([System.String]::Format('$(ErrorText)', '$(WasdkNuget)\build\native\Microsoft.WindowsAppSDK.targets'))" />
     <Error Condition="!Exists('$(WebView2Nuget)\build\native\Microsoft.Web.WebView2.targets')" Text="$([System.String]::Format('$(ErrorText)', '$(WebView2Nuget)\build\native\Microsoft.Web.WebView2.targets'))" />
   </Target>
-</Project>
+</Project>

src/modules/cmdpal/extensionsdk/Microsoft.CommandPalette.Extensions/packages.config

@@ -1,7 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Microsoft.Web.WebView2" version="1.0.2903.40" targetFramework="native" />
   <package id="Microsoft.Windows.CppWinRT" version="2.0.240111.5" targetFramework="native" />
   <package id="Microsoft.Windows.SDK.BuildTools" version="10.0.26100.4188" targetFramework="native" />
-  <package id="Microsoft.WindowsAppSDK" version="1.7.250513003" targetFramework="native" />
 </packages>