Rename Package Icon file only when packing

Every "official" .NET packages use 'Icon' as its file name.
Since, the icon file itself is public and older packages refer them by URL,
we only change the file name during packaging which would be in the package.

Microsoft.Toolkit.Uwp.Notifications/Microsoft.Toolkit.Uwp.Notifications.nuspec

@@ -8,7 +8,7 @@
     <license type="expression">MIT</license>
     <projectUrl>https://github.com/CommunityToolkit/WindowsCommunityToolkit</projectUrl>
     <iconUrl>https://raw.githubusercontent.com/CommunityToolkit/WindowsCommunityToolkit/main/build/nuget.png</iconUrl>
-    <icon>images\nuget.png</icon>
+    <icon>Icon.png</icon>
     <description>The official way to send toast notifications on Windows 10 via code rather than XML, with the help of IntelliSense. Supports all C# app types, including WPF, UWP, WinForms, and Console, even without packaging your app as MSIX. Also supports C++ UWP apps.
 
       Additionally, generate notification payloads from your ASP.NET web server to send as push notifications, or generate notification payloads from class libraries.
@@ -52,7 +52,7 @@
     </dependencies>
   </metadata>
   <files>
-    <file src="..\build\nuget.png" target="images\" />
+    <file src="..\build\nuget.png" target="Icon.png" />
     <file src="..\license.md" target="" />
     <file src="Microsoft.Toolkit.Uwp.Notifications.targets" target="build\native\Microsoft.Toolkit.Uwp.Notifications.targets" />
     <file src="$buildOutput$\net461\Microsoft.Toolkit.Uwp.Notifications.dll" target="lib\net461\Microsoft.Toolkit.Uwp.Notifications.dll" />

build/Windows.Toolkit.Common.props

@@ -10,7 +10,7 @@
     <Copyright>(c) .NET Foundation and Contributors.  All rights reserved.</Copyright>
     <PackageProjectUrl>https://github.com/CommunityToolkit/WindowsCommunityToolkit</PackageProjectUrl>
     <PackageReleaseNotes>https://github.com/CommunityToolkit/WindowsCommunityToolkit/releases</PackageReleaseNotes>
-    <PackageIcon>nuget.png</PackageIcon>
+    <PackageIcon>Icon.png</PackageIcon>
     <PackageIconUrl>https://raw.githubusercontent.com/CommunityToolkit/WindowsCommunityToolkit/master/build/nuget.png</PackageIconUrl>
   </PropertyGroup>
 

build/Windows.Toolkit.Common.targets

@@ -13,7 +13,7 @@
   </PropertyGroup>
 
   <ItemGroup Condition="$(IsPackable)">
-    <None Include="$(BuildToolsDirectory)nuget.png" Pack="true" PackagePath="\" />
+    <None Include="$(BuildToolsDirectory)nuget.png" Pack="true" PackagePath="\Icon.png" />
     <None Include="$(RepositoryDirectory)License.md" Pack="true" PackagePath="\" />
   </ItemGroup>