Windows ML: Fix warnings in cs-winui project (#546)

* Fix warnings in cs-winui project

* PR feedback (add publish profiles)

* Revert "PR feedback (add publish profiles)"

This reverts commit 340e2fd.

* Remove PublishProfile

---------

Co-authored-by: Aditya Rastogi <adityar@ntdev.microsoft.com>

Author: adrastogi

Samples/WindowsML/cs-winui/WindowsMLSample.csproj

@@ -3,12 +3,12 @@
     <OutputType>WinExe</OutputType>
     <RootNamespace>WindowsMLSample</RootNamespace>
     <ApplicationManifest>app.manifest</ApplicationManifest>
-    <PublishProfile>win-$(Platform).pubxml</PublishProfile>
     <UseWinUI>true</UseWinUI>
     <EnableMsixTooling>true</EnableMsixTooling>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <GenerateAppInstallerFile>False</GenerateAppInstallerFile>
-    <AppxPackageSigningEnabled>True</AppxPackageSigningEnabled>
+    <AppxPackageSigningEnabled Condition="'$(AppxPackageSigningEnabled)' == '' and ('$(PackageCertificateThumbprint)' != '' or '$(PackageCertificateKeyFile)' != '')">True</AppxPackageSigningEnabled>
+    <AppxPackageSigningEnabled Condition="'$(AppxPackageSigningEnabled)' == ''">False</AppxPackageSigningEnabled>
     <AppxPackageSigningTimestampDigestAlgorithm>SHA256</AppxPackageSigningTimestampDigestAlgorithm>
     <AppxAutoIncrementPackageRevision>False</AppxAutoIncrementPackageRevision>
     <AppxSymbolPackageEnabled>False</AppxSymbolPackageEnabled>