Use NormalizeDirectory consistently in SiteExtensions D.B.P (#61455)

* Use NormalizeDirectory consistently in SiteExtensions D.B.P

* Refactor MSBuild property definitions

src/SiteExtensions/Directory.Build.props

@@ -2,11 +2,12 @@
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory)..\, Directory.Build.props))\Directory.Build.props" />
 
   <PropertyGroup>
-    <MicrosoftWebXdtExtensionsPath>$(ArtifactsBinDir)Microsoft.Web.Xdt.Extensions\$(Configuration)\net462\Microsoft.Web.Xdt.Extensions.dll</MicrosoftWebXdtExtensionsPath>
-    <MicrosoftWebXdtExtensionsPath Condition="'$(DotNetBuildPass)' == '2'">$(ArtifactsBinDir)Microsoft.Web.Xdt.Extensions\$(TargetArchitecture)\$(Configuration)\net462\Microsoft.Web.Xdt.Extensions.dll</MicrosoftWebXdtExtensionsPath>
+    <MicrosoftWebXdtExtensionsDir>$([MSBuild]::NormalizeDirectory('$(ArtifactsBinDir)', 'Microsoft.Web.Xdt.Extensions', '$(Configuration)', 'net462'))</MicrosoftWebXdtExtensionsDir>
+    <MicrosoftWebXdtExtensionsDir Condition="'$(DotNetBuildPass)' == '2'">$([MSBuild]::NormalizeDirectory('$(ArtifactsBinDir)', 'Microsoft.Web.Xdt.Extensions', '$(TargetArchitecture)', '$(Configuration)', 'net462'))</MicrosoftWebXdtExtensionsDir>
+    <MicrosoftWebXdtExtensionsPath>$(MicrosoftWebXdtExtensionsDir)Microsoft.Web.Xdt.Extensions.dll</MicrosoftWebXdtExtensionsPath>
     <BaseIntermediateOutputPath Condition="'$(DotNetBuildPass)' == '2'">$([MSBuild]::NormalizeDirectory('$(BaseIntermediateOutputPath)', '$(TargetArchitecture)'))</BaseIntermediateOutputPath>
-    <IntermediateOutputPath Condition="'$(PlatformName)' == 'AnyCPU' AND '$(DotNetBuildPass)' == '2'">$(BaseIntermediateOutputPath)$(Configuration)\</IntermediateOutputPath>
-    <IntermediateOutputPath Condition="'$(PlatformName)' != 'AnyCPU' AND '$(DotNetBuildPass)' == '2'">$(BaseIntermediateOutputPath)$(PlatformName)\$(Configuration)\</IntermediateOutputPath>
+    <IntermediateOutputPath Condition="'$(PlatformName)' == 'AnyCPU' AND '$(DotNetBuildPass)' == '2'">$([MSBuild]::NormalizeDirectory('$(BaseIntermediateOutputPath)', '$(Configuration)'))</IntermediateOutputPath>
+    <IntermediateOutputPath Condition="'$(PlatformName)' != 'AnyCPU' AND '$(DotNetBuildPass)' == '2'">$([MSBuild]::NormalizeDirectory('$(BaseIntermediateOutputPath)', '$(PlatformName)', '$(Configuration)'))</IntermediateOutputPath>
   </PropertyGroup>
 
-</Project>
+</Project>