20250310：OpenCV mat对象与base64互转
代码：
https://github.com/ReneNyffenegger/cpp-base64
指南：https://renenyffenegger.ch/notes/development/Base64/Encoding-and-decoding-base-64-with-cpp/
实操：
代码：
https://github.com/ReneNyffenegger/cpp-base64
指南：https://renenyffenegger.ch/notes/development/Base64/Encoding-and-decoding-base-64-with-cpp/
实操：