.Net: Reverting Onnx from 0.5.0 to 0.4.0 (#9658)

### Motivation and Context

Reverting to 0.4.0 as the strategy to upgrade to 0.5.0 is not ready yet,
the resource management of the new version adds some extra complexity to
the caller that needs to be better addressed in a future PR.

dotnet/Directory.Packages.props

@@ -39,7 +39,7 @@
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.3.0" />
     <PackageVersion Include="Microsoft.Bcl.TimeProvider" Version="8.0.1" />
     <PackageVersion Include="Microsoft.Identity.Client" Version="4.66.1" />
-    <PackageVersion Include="Microsoft.ML.OnnxRuntime" Version="1.20.0" />
+    <PackageVersion Include="Microsoft.ML.OnnxRuntime" Version="1.19.2" />
     <PackageVersion Include="FastBertTokenizer" Version="1.0.28" />
     <PackageVersion Include="PdfPig" Version="0.1.9" />
     <PackageVersion Include="Pinecone.NET" Version="2.1.1" />
@@ -150,8 +150,8 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <!-- OnnxRuntimeGenAI -->
-    <PackageVersion Include="Microsoft.ML.OnnxRuntimeGenAI" Version="0.5.0" />
-    <PackageVersion Include="Microsoft.ML.OnnxRuntimeGenAI.Cuda" Version="0.5.0" />
-    <PackageVersion Include="Microsoft.ML.OnnxRuntimeGenAI.DirectML" Version="0.5.0" />
+    <PackageVersion Include="Microsoft.ML.OnnxRuntimeGenAI" Version="0.4.0" />
+    <PackageVersion Include="Microsoft.ML.OnnxRuntimeGenAI.Cuda" Version="0.4.0" />
+    <PackageVersion Include="Microsoft.ML.OnnxRuntimeGenAI.DirectML" Version="0.4.0" />
   </ItemGroup>
 </Project>