replace boost::filesystem with std::filesystem

[antond-weta]

No description provided.

[soswow]

duplicate of 9th line

[antond-weta]

done

[soswow]

Do we want to make it blow up if 17 requirement is not met:

On Line 3:

if(NOT DEFINED CMAKE_CXX_STANDARD)
  set(CMAKE_CXX_STANDARD 17)
endif()
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

[antond-weta]

Sure, why not. I'm using some of C++20 features in my v2 branch, so this is getting complicated.

[antond-weta]

done

[soswow]

What do you of this:

The goal is to prefer CMake package config (vcpkg/Conan), fall back to FindBoost for distro installs

find_package ( Boost         CONFIG QUIET
    COMPONENTS
        system
        unit_test_framework
)
if (NOT Boost_FOUND)
    find_package ( Boost REQUIRED
        COMPONENTS
            system
            unit_test_framework
    )
endif()

[antond-weta]

I'm not too worried about this. Boost is going away in the next couple of PRs. Definitely before the next release.