Re-add netframework targeting for Tools.proj PackageRef compat (#15273)

Author: mmitche

src/Microsoft.DotNet.MacOsPkg/Microsoft.DotNet.MacOsPkg.csproj

@@ -1,15 +1,19 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>$(NetToolCurrent)</TargetFramework>
+    <!-- We include both netframework and netcore in the target frameworks because Arcade's Tools.proj
+         'targets' via net472. -->
+    <TargetFrameworks>$(NetToolCurrent);$(NetFrameworkToolCurrent)</TargetFrameworks>
     <OutputType>Exe</OutputType>
     <Nullable>enable</Nullable>
     <IsPackable>true</IsPackable>
     <Description>The MacOsPkg tool is used for unpacking and packing MacOS .pkg files and nested .app bundles.</Description>
     <PackageTags>Arcade Build Tool MacOS Pkg</PackageTags>
     <DevelopmentDependency>false</DevelopmentDependency>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(TargetFramework)' == '$(NetToolCurrent)'">
     <PackAsTool>true</PackAsTool>
     <ToolCommandName>dotnet-macos-pkg</ToolCommandName>
   </PropertyGroup>
-
 </Project>