This pull request modernizes the OPC UA .NET codebase and tests, removes .NET Standard 2.0 support from certificate/security code, and updates test code to use C# 12 and .NET 8+ features for clarity and maintainability.
- Certificate and BouncyCastle interop files (e.g., CertificateBuilder.cs, X509Extensions.cs, X509SignatureFactory.cs) are refactored to drop NETSTANDARD2_0 support and use modern .NET APIs and conditional compilation.
- Test code across the codebase is updated to use default, strongly-typed Parse methods, collection expressions, and improved async/await patterns.
- Exception handling and assertions in tests are modernized, and test method naming is made consistent with Async suffixes.
- The project and build files are updated to clarify Roslynator analyzer usage and remove obsolete netstandard tags.
- General code and test cleanup includes improved null safety, type safety, and removal of deprecated or unused code.
- Add a solution to provide fuzzer support for afl-fuzz and libfuzzer.
- Add fuzz targets for Binary, Json and Xml encoder and decoder fuzzing. For afl-fuzz and libfuzzer.
- Fix issues in encoders and decoders when unexpected exceptions are returned. The expectation is to return only ServiceResultException with BadDecodingError, BadEncodingError or BadEncodingLimitsExceeded.
- Add a tool to create Testcases.
- Add a tool to playback crashes and timeouts.
- Solution is extensible with common files to discover new fuzz targets by reflection. New fuzz projects can share many files with the first project.
- Breaking change: Fix how BinaryDecoder is used: Previously, calling close on the BinaryDecoder implicitly disposed the stream. Change behavior so that `using` pattern can be applied across the board.
Marc Schier