Add .NET 8.0 C# port of OpenV2G EXI codec

- Port core EXI encoding/decoding functionality to C#
- Implement V2G protocol parsing and analysis
- Add simplified decoder/encoder for roundtrip testing
- Create comprehensive error handling with EXI exceptions
- Support both byte array and file stream operations
- Include packet structure analysis for V2GTP data
- Successfully builds and runs basic functionality tests

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

csharp/dotnet/obj/project.nuget.cache

@@ -0,0 +1,8 @@
+{
+  "version": 2,
+  "dgSpecHash": "YcIrz6PQqRE=",
+  "success": true,
+  "projectFilePath": "C:\\Data\\Source\\SIMP\\V2GDecoderC\\csharp\\dotnet\\V2GDecoderNet.csproj",
+  "expectedPackageFiles": [],
+  "logs": []
+}