[Feature Request] Update logging system to use format included in C++ standard

[jopadan]

std::format
std::formatter<std::filesystem::path>

• remove 3rdparty/fmt and GTest
• adapt the code to use format version included in C++ standard

#include <filesystem>
#include <format>
namespace logging
{
/* adapt code here */
};

[ericwa]

• we use the fmt::color:: terminal color features in fmt so that would need a replacement
• time to compile the C++ code is a priority for us, and the std::format has worse compile times than libfmt when I've tried. We also use it in practically every source file so small improvements add up here.
• Not bundling GTest is possible, but then how do we obtain it for CI? For devs on Windows? (vcpkg I guess is the obvious way.)

if you're wanting to avoid bundled libs, we could avoid downloading GTest if DISABLE_TESTS is set.