base64 library from github: https://github.com/ReneNyffenegger/cpp-base64, merged .cpp and .h files together.
NOTE
used for encoding image to base64 string when interact with mLLM in VidepPipe.
test file base64_test.cpp, which convert cv::Mat to base64 string and convert back to cv::Mat
mkdir build
cd build
cmake ..
make -j8
./base64_test