add cpp test file

[nealwang123]

No description provided.

[nealwang123]

重构isotp_test.cpp实现多线程UDS诊断测试：
使用结构体数组存储UDS请求及长度
添加线程同步和消息转发
实现完整的请求/响应测试流程
This pull request includes several significant changes to the project, focusing on adding a test program, improving debugging capabilities, and updating the build configuration. The most important changes are summarized below:

Build Configuration Updates:

• CMakeLists.txt: Updated to include C++ language support, set C and C++ standards, and added build and install configurations for the isotp library and a new test program isotp_test.
• Makefile: Added a new test target to build and run the isotp_test program. [1] [2]

Debugging Enhancements:

• isotp.c: Added debug output statements in the isotp_poll function to log details about sent frames and transmission completion. [1] [2]
• isotp_user_impl.c: Implemented debug output and simulated CAN send and get time functions for testing purposes.

Test Program Addition:

• isotp_test.cpp: Added a comprehensive test program that includes thread synchronization, CAN message simulation, and UDS diagnostic request handling.

[nealwang123]

目前仅在windows下配合msvc2019进行了验证，后续会结合qt canbus配合硬件进行验证