Modernize and enhance the libfastrace C++ API

[ethercflow]

I think we need to improve the C++ interface of libfastrace to make it more robust, safer, and easier to use. This issue tracks the following enhancements:

1. Replace C-style API calls with idiomatic C++ wrappers
2. Implement RAII principles for better resource management
3. Add move semantics to key classes (Span, LocalSpan)
4. Improve type safety in Rust-C++ interoperability
5. Enhance property handling with vector-based APIs
6. Refactor type conversions to use modern C++ practices
7. Update example code to demonstrate new API usage
8. Improve overall code readability and maintainability

Acceptance Criteria:

• All C++ classes (Span, LocalSpan, etc.) have proper RAII implementations
• Move semantics are correctly implemented for transferable objects
• The new API is type-safe and prevents common usage errors
• Example code compiles and runs correctly with the new API
• No performance regression in core operations
• Code passes all existing tests and any new tests added for new functionality
• Documentation is updated to reflect API changes

Additional Notes:

• This refactoring should not change the underlying functionality of libfastrace
• Backward compatibility should be considered, with a clear migration path for existing users if breaking changes are introduced