[workload] Use the same naming as net9 workload (#103049)

* Use the same naming as net9 workload

* Add aliases to the versioned packs

* Fixup AOTCompiler import

* Fix aliases

* Update WorkloadManifest.json.in

Fix alias

* Update WorkloadManifest.targets.in

Author: lewing

src/mono/nuget/Microsoft.NET.Workload.Mono.Toolchain.Current.Manifest/Microsoft.NET.Workload.Mono.Toolchain.Current.Manifest.pkgproj

@@ -42,6 +42,7 @@
     </PropertyGroup>
 
     <ItemGroup>
+      <_WorkloadManifestValues Include="NetVersion" Value="net8" />
       <_WorkloadManifestValues Include="WorkloadVersion" Value="$(PackageVersion)" />
       <_WorkloadManifestValues Include="PackageVersion" Value="$(PackageVersion)" />
       <_WorkloadManifestValues Include="PackageVersionNet6" Value="$(PackageVersionNet6)" />