Warn when building C++/CLI tests not in a command prompt and don't tr…

…y copying the files if we aren't in one (dotnet#96465)

This will allow devs to use dotnet build to build the Interop test suite and still run non C++/CLI tests while using `dotnet build`.

src/tests/Interop/Directory.Build.targets

@@ -11,8 +11,9 @@
   <Target Name="CopyInteropNativeRuntimeDependencies"
     BeforeTargets="CopyAllNativeProjectReferenceBinaries"
     Condition="'$(TargetsWindows)' == 'true' And ('$(Configuration)' == 'Debug' Or '$(Configuration)' == 'Checked') And '$(CopyDebugCRTDllsToOutputDirectory)' == 'true'" >
+    <Warning Message="Building C++/CLI tests requires a Visual Studio Dev Command Prompt" Condition="'$(VCToolsRedistDir)' == '' or '$(ExtensionSdkDir)' == ''" />
     <!-- Required debug vcruntime and UCRT dlls -->
-    <ItemGroup>
+    <ItemGroup Condition="'$(VCToolsRedistDir)' != '' and '$(ExtensionSdkDir)' != ''">
       <InteropNativeRuntimeDependencies Include="$(VCToolsRedistDir)onecore/debug_nonredist/$(TargetArchitecture)/Microsoft.VC*.DebugCRT/vcruntime*d.dll" />
       <InteropNativeRuntimeDependencies Include="$(VCToolsRedistDir)onecore/debug_nonredist/$(TargetArchitecture)/Microsoft.VC*.DebugCRT/msvcp*d.dll" />
       <InteropNativeRuntimeDependencies Include="$(ExtensionSdkDir)/Microsoft.UniversalCRT.Debug/$(UCRTVersion)/Redist/Debug/$(TargetArchitecture)/ucrtbased.dll" />