Include .Views.dll from single file in .NET Core 3.1 apps (#27897)

For 5.0, we made a change to exclude .Views.dll from the single file bundle as a reaction
to changes in bundling. However the SDK change also applied to .NET 3.1 apps. This change
limits the exclusion to 5.0 and newer apps.

Fixes #27831

Author: pranavkm

src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Sdk.Razor.CurrentVersion.targets

@@ -724,12 +724,13 @@ Copyright (c) .NET Foundation. All rights reserved.
       <AllPublishItemsFullPathWithTargetPath Include="@(RazorIntermediateAssembly->'%(FullPath)')">
         <TargetPath>%(Filename)%(Extension)</TargetPath>
         <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
-        <ExcludeFromSingleFile>true</ExcludeFromSingleFile>
+        <!-- .Views.dll and .Views.pdb were part of the single file bundle in 3.1 apps. Lets keep this unchanged. -->
+        <ExcludeFromSingleFile Condition="'$(_TargetingNET50OrLater)' == 'true'">true</ExcludeFromSingleFile>
       </AllPublishItemsFullPathWithTargetPath>
       <AllPublishItemsFullPathWithTargetPath Include="@(_RazorDebugSymbolsIntermediatePath->'%(FullPath)')">
         <TargetPath>%(Filename)%(Extension)</TargetPath>
         <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
-        <ExcludeFromSingleFile>true</ExcludeFromSingleFile>
+        <ExcludeFromSingleFile Condition="'$(_TargetingNET50OrLater)' == 'true'">true</ExcludeFromSingleFile>
       </AllPublishItemsFullPathWithTargetPath>
     </ItemGroup>