Build: Use a dependency manager for bundled dependencies

[CyberTailor]

Manual dependency management leaves room for error.

I suggest using Hunter or Conan for managing bundled third-party libraries (like Boost, tclap, utfcpp etc.)

[IhorShevchuk]

I vote for using FetchContent that is already built into CMake and will not bring one more additional tool that will require support.
But I am not sure if this particular project uses anything else except Boost and cURL.