Remove redundant empty Pack target

- Remove the empty Pack target from all project files.
- Put the empty Pack target in `Directory.Build.targets`.

Author: Nirmal4G

Directory.Build.targets

@@ -31,4 +31,10 @@
     </ItemGroup>
   </Target>
 
+  <!--
+      Define an empty Pack target to avoid error when packing solution from command-line.
+      This gets overridden by the actual Pack target imported by the .NET SDK.
+  -->
+  <Target Name="Pack" />
+
 </Project>

GazeInputTest/GazeInputTest.csproj

@@ -155,6 +155,4 @@
     <VisualStudioVersion>14.0</VisualStudioVersion>
   </PropertyGroup>
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

Microsoft.Toolkit.Uwp.SampleApp/Microsoft.Toolkit.Uwp.SampleApp.csproj

@@ -1562,6 +1562,4 @@
       </AppxPackagePayload>
     </ItemGroup>
   </Target>
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

Microsoft.Toolkit.Uwp.Samples.BackgroundTasks/Microsoft.Toolkit.Uwp.Samples.BackgroundTasks.csproj

@@ -137,6 +137,4 @@
     <ErrorReport>prompt</ErrorReport>
   </PropertyGroup>
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

Microsoft.Toolkit.Win32.WpfCore.SampleApp.PackagingProject/Microsoft.Toolkit.Win32.WpfCore.SampleApp.PackagingProject.wapproj

@@ -76,6 +76,4 @@
     </ProjectReference>
   </ItemGroup>
   <Import Project="$(WapProjPath)\Microsoft.DesktopBridge.targets" />
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

SmokeTests/SmokeTest.csproj

@@ -129,6 +129,4 @@
     <Error Condition="'@(NuGetPackageFiltered)' == '' and $(CurrentProject) != 'UWPBaseline' and '$(CurrentProject)' != 'UWPBaselineWinUI'" Text="NuGet '$(CurrentProject).[SEMVER].nupkg' doesn't exist!" />
     <Error Condition="'$(CurrentProject)' != 'UWPBaseline' and '$(CurrentProject)' != 'UWPBaselineWinUI' and '$(NuGetPackageVersion)' == 'To Fill In With Local Version Number'" Text="Please set 'NuGetPackageVersion' at the top of 'SmokeTest.csproj' with the version to smoke test locally." />
   </Target>
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

UITests/UITests.App/UITests.App.csproj

@@ -250,6 +250,4 @@
   </PropertyGroup>
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
   <Import Project="..\UITests.Tests.Shared\UITests.Tests.Shared.projitems" Label="Shared" />
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

UnitTests/UnitTests.Notifications.UWP/UnitTests.Notifications.UWP.csproj

@@ -171,6 +171,4 @@
     <VisualStudioVersion>14.0</VisualStudioVersion>
   </PropertyGroup>
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

UnitTests/UnitTests.Notifications.WinRT/UnitTests.Notifications.WinRT.csproj

@@ -169,6 +169,4 @@
     </Reference>
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>

UnitTests/UnitTests.UWP/UnitTests.UWP.csproj

@@ -538,6 +538,4 @@
     <Prefer32Bit>true</Prefer32Bit>
   </PropertyGroup>
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
-  <!-- No-op to avoid build error when packing solution from commandline -->
-  <Target Name="Pack" />
 </Project>