Added nuspec file to package both uap and net9 targeted uwp libraries together

Author: aborziak-ms

.gitignore

@@ -234,4 +234,7 @@ msbuild.binlog
 LottieGenOutput-*/
 
 # Visual Studio debugging configuration file.
-launchSettings.json
+launchSettings.json
+
+# Nuget Package files.
+pack/

Lottie-Windows/Lottie-Windows-WinUI3/Lottie-Windows-WinUI3.csproj

@@ -7,6 +7,7 @@
 
     <PackageId>CommunityToolkit.WinUI.Lottie</PackageId>
     <PackageTags>WinUI3 Toolkit Windows Animations Lottie XAML</PackageTags>
+    <IsPackable>True</IsPackable>
 
     <Nullable>enable</Nullable>
     <CsWinRTIncludes>Microsoft</CsWinRTIncludes>

Lottie-Windows/Lottie-Windows.props

@@ -7,7 +7,6 @@
 
     <!-- Nuget props-->
     <Description>This library provides the LottieVisualSource which is consumed by the Microsoft.UI.Xaml.Controls.AnimatedVisualPlayer to render Lottie JSON files.</Description>
-    <IsPackable>True</IsPackable>
 
     <LangVersion>latest</LangVersion>
     <DocumentationFile>bin\AnyCPU\Release\CommunityToolkit.WinUI.Lottie.xml</DocumentationFile>

build/Lottie-Windows-Uwp.nuspec

@@ -0,0 +1,42 @@
+<?xml version="1.0"?>
+<package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
+  <metadata>
+    <id>CommunityToolkit.UwpUnified.Lottie</id>
+    <version>0.0.0-SpecifyVersionOnCommandline</version>
+    <authors>Microsoft.Toolkit</authors>
+    <requireLicenseAcceptance>true</requireLicenseAcceptance>
+    <licenseUrl>https://github.com/windows-toolkit/Lottie-Windows/blob/master/license.md</licenseUrl>
+    <projectUrl>https://github.com/windows-toolkit/Lottie-Windows</projectUrl>
+    <iconUrl>https://raw.githubusercontent.com/windows-toolkit/WindowsCommunityToolkit/master/build/nuget.png</iconUrl>
+    <description>This library provides the LottieVisualSource which is consumed by the Microsoft.UI.Xaml.Controls.AnimatedVisualPlayer to render Lottie JSON files in runtime.</description>
+    <releaseNotes>Release https://github.com/windows-toolkit/Lottie-Windows/releases</releaseNotes>
+    <copyright>(c) .NET Foundation and Contributors.  All rights reserved.</copyright>
+    <tags>UWP Toolkit Windows Animations Lottie XAML</tags>
+    <dependencies>
+      <group targetFramework="net9.0-windows10.0.26100">
+        <dependency id="Microsoft.UI.Xaml" version="2.8.7" />
+        <dependency id="Microsoft.Windows.CsWinRT" version="2.2.0" />
+        <dependency id="Win2D.uwp" version="1.28.2" />
+      </group>
+      <group targetFramework="uap10.0.16299">
+        <dependency id="Microsoft.UI.Xaml" version="2.5.0" exclude="Build,Analyzers" />
+        <dependency id="Win2D.uwp" version="1.25.0" exclude="Build,Analyzers" />
+        <dependency id="System.Memory" version="4.5.5" exclude="Build,Analyzers" />
+        <dependency id="System.Numerics.Vectors" version="4.5.0" exclude="Build,Analyzers" />
+        <dependency id="System.Runtime.CompilerServices.Unsafe" version="6.0.0" exclude="Build,Analyzers" />
+        <dependency id="System.Text.Encodings.Web" version="9.0.0" exclude="Build,Analyzers" />
+        <dependency id="System.Text.Json" version="9.0.0" exclude="Build,Analyzers" />
+        <dependency id="System.ValueTuple" version="4.5.0" exclude="Build,Analyzers" />
+      </group>
+    </dependencies>
+    <frameworkReferences>
+      <group targetFramework="net9.0-windows10.0.26100">
+        <frameworkReference name="Microsoft.Windows.SDK.NET.Ref.Xaml" />
+      </group>
+    </frameworkReferences>
+  </metadata>
+
+  <files>
+    <file src="bin\pack\lib\**" target="lib" />
+  </files>
+</package>

build/build.cake

@@ -244,6 +244,20 @@ Task("Package")
     // Invoke the pack target to generate the code to be packed.
     MSBuildSolution("Pack", ("GenerateLibraryLayout", "true"), ("PackageOutputPath", nupkgDir));
 
+    var stage   = Directory("./pack");
+
+    var net9Dir = stage + Directory("lib") + Directory("net9.0-windows10.0.26100.0");
+    var uapDir  = stage + Directory("lib") + Directory("uap10.0.16299");
+
+    // clean & recreate
+    CleanDirectory(stage);
+    EnsureDirectoryExists(net9Dir);
+    EnsureDirectoryExists(uapDir);
+
+    // copy the Release builds
+    CopyFiles($"{baseDir}/Lottie-Windows/Lottie-Windows-UwpNet/bin/{configuration}/net9.0-windows10.0.26100.0/*", net9Dir);
+    CopyFiles($"{baseDir}/Lottie-Windows/Lottie-Windows-Uwp/bin/{configuration}/uap10.0.16299/*",             uapDir);
+
     foreach (var nuspec in GetFiles("./*.nuspec"))
     {
         var nuGetPackSettings = new NuGetPackSettings