Never pack NuGetizer transitively

This stops inference from collecting transitive dependency files from NuGetizer and packing them too alongisde the consuming project.

This is currently an issue since due to being a development dependency, NuGetizer will by default install with a `PrivateAssets=all` value, which for packing purposes means "pack everything this dependency brings, transitively, into this package output", since that's the most common scenario.

But for build-only packages like NuGetizer, it doesn't make sense. Especially for non-build transitive assets such as analyzer's localization files (i.e. SponsorLink in NuGetizer's case).

So we default this to the most obvious value now.

Author: kzu

src/NuGetizer.Tasks/NuGetizer.Inference.targets

@@ -190,9 +190,14 @@ Copyright (c) .NET Foundation. All rights reserved.
       _SetPackTargetFramework;
       InferPackageContents
     </GetPackageContentsDependsOn>
-
   </PropertyGroup>
 
+  <ItemGroup>
+    <!-- NuGetizer should never pack transitively (i.e. SponsorLink assets), even 
+         when PrivateAssets=all is used due to being a development dependency now. -->
+    <PackageReference Update="NuGetizer" PackTransitively="false" />    
+  </ItemGroup>
+
   <Target Name="_SetDefaultPackageReferencePack" Condition="'$(PackFolder)' == 'build' or '$(PackFolder)' == 'buildTransitive'"
           BeforeTargets="InferPrimaryOutputDependencies;InferPackageContents">
     <ItemGroup>