Enable NuGetAudit and perform clean-up (#604)

* Enable NuGetAudit and perform clean-up

- Remove unnecessary package source feeds
- Remove the unnecessary source build prebuilt
  base line file

* Delete eng/Xdt.snk

* Update Directory.Build.props

* Update Directory.Build.props

Author: ViktorHofer

Directory.Build.props

@@ -5,7 +5,6 @@
   <PropertyGroup>
     <Copyright>$(CopyrightMicrosoft)</Copyright>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
-    <AssemblyOriginatorKeyFile>$(RepositoryEngineeringDir)WebSdk.snk</AssemblyOriginatorKeyFile>
     <LangVersion>latest</LangVersion>
   </PropertyGroup>
 
@@ -20,6 +19,9 @@
     <PackageTags>Microsoft Xdt XmlDocumentTransform XmlTransform</PackageTags>
     <RepositoryUrl>https://github.com/dotnet/xdt</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <!-- Only upgrade NuGetAudit warnings to errors for official builds. -->
+    <WarningsNotAsErrors Condition="'$(OfficialBuild)' != 'true'">$(WarningsNotAsErrors);NU1901;NU1902;NU1903;NU1904</WarningsNotAsErrors>
   </PropertyGroup>
 
 </Project>

NuGet.config

@@ -2,15 +2,12 @@
 <configuration>
   <packageSources>
     <clear />
-    <add key="dotnet8" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet8/nuget/v3/index.json" />
-    <add key="dotnet8-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet8-transport/nuget/v3/index.json" />
     <add key="dotnet-eng" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json" />
     <add key="dotnet-public" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json" />
-    <add key="nuget-build" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/nuget-build/nuget/v3/index.json" />
-    <add key="dotnet-tools" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json" />
-    <add key="dotnet-tools-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools-transport/nuget/v3/index.json" />
-    <add key="dotnet-libraries" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-libraries/nuget/v3/index.json" />
-    <add key="dotnet-libraries-transport" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-libraries-transport/nuget/v3/index.json" />
   </packageSources>
+  <auditSources>
+    <clear />
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
+  </auditSources>
   <disabledPackageSources />
 </configuration>