Add System.CodeDom/8.0.0 needed by roslyn (#1232)

Unblocks dotnet/roslyn#78213

Author: ViktorHofer

azure-pipelines/templates/stages/build.yml

@@ -9,7 +9,7 @@ stages:
     pool:
       ${{ if eq(variables['System.TeamProject'], 'public') }}:
         name: $(DncEngPublicBuildPool)
-        demands: ImageOverride -equals Build.Ubuntu.1804.Amd64.Open
+        demands: ImageOverride -equals Build.Ubuntu.2204.Amd64.Open
       ${{ if eq(variables['System.TeamProject'], 'internal') }}:
         name: $(DncEngInternalBuildPool)
         image: 1es-ubuntu-2204

eng/Build.props

@@ -43,6 +43,8 @@
     <DependencyPackageProjects Include="$(RepoRoot)src\referencePackages\src\**\System.Memory.4.6.3.csproj" />
     <DependencyPackageProjects Include="$(RepoRoot)src\referencePackages\src\**\System.Threading.Tasks.Extensions.4.6.3.csproj" />
     <DependencyPackageProjects Include="$(RepoRoot)src\referencePackages\src\**\System.Net.WebSockets.WebSocketProtocol.5.1.3.csproj" />
+
+    <DependencyPackageProjects Include="$(RepoRoot)src\referencePackages\src\**\System.CodeDom.8.0.0.csproj" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(BuildDependencyPackageProjects)' == 'true'">

src/referencePackages/src/system.codedom/8.0.0/System.CodeDom.8.0.0.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>net6.0;net7.0;net8.0;netstandard2.0</TargetFrameworks>
+    <AssemblyName>System.CodeDom</AssemblyName>
+    <StrongNameKeyId>Open</StrongNameKeyId>
+  </PropertyGroup>
+
+</Project>