- Enhance CMakeLists.txt files. - Move to Boost Test from Google Test to support pre-C++11 compilers. - Add more configurations on CI matrix builds. - Other minor fixes
std::byte
`std::byte` is mapped to https://github.com/msgpack/msgpack/blob/master/spec.md#int-format-family. `std::vector<std::byte>` and `std::byte[]` are mapped to https://github.com/msgpack/msgpack/blob/master/spec.md#bin-format-family.