Allow setting KnownAppHostPack and KnownRuntimePack (#46735)

Author: ayakael

eng/tools/GenerateFiles/Directory.Build.targets.in

@@ -42,6 +42,18 @@
        <RuntimePackRuntimeIdentifiers Condition=" '$(PortableBuild)' == 'false' ">$(TargetRuntimeIdentifier)</RuntimePackRuntimeIdentifiers>
     </KnownFrameworkReference>
 
+    <KnownAppHostPack Update="Microsoft.NETCore.App">
+      <AppHostPackVersion
+        Condition=" '%(TargetFramework)' == '${DefaultNetCoreTargetFramework}' ">${MicrosoftNETCoreAppRuntimeVersion}</AppHostPackVersion>
+      <AppHostRuntimeIdentifiers Condition=" '$(PortableBuild)' == 'false' ">$(TargetRuntimeIdentifier)</AppHostRuntimeIdentifiers>
+    </KnownAppHostPack>
+
+    <KnownRuntimePack Update="Microsoft.NETCore.App">
+      <LatestRuntimeFrameworkVersion
+        Condition=" '%(TargetFramework)' == '${DefaultNetCoreTargetFramework}' ">${MicrosoftNETCoreAppRuntimeVersion}</LatestRuntimeFrameworkVersion>
+      <AppHostRuntimeIdentifiers Condition=" '$(PortableBuild)' == 'false' ">$(TargetRuntimeIdentifier)</AppHostRuntimeIdentifiers>
+    </KnownRuntimePack>
+
     <KnownCrossgen2Pack Update="Microsoft.NETCore.App.Crossgen2" Condition=" '$(PortableBuild)' == 'false' ">
       <Crossgen2PackVersion
           Condition=" '%(TargetFramework)' == '${DefaultNetCoreTargetFramework}' ">${MicrosoftNETCoreAppRuntimeVersion}</Crossgen2PackVersion>