Add backport of std::expected instead of Result.hpp

[synacker]

Is your feature request related to a problem? Please describe. Result.hpp is developer defined code for std::expected functionality. std::expected inroduced in C++23, but project standard is C++17.

Describe the solution you'd like Replace Result.hpp by std::expected backport to C++17.

Describe alternatives you've considered https://github.com/zeus-cpp/expected - good solution for C++17

Additional context Need to be sure, that file can be placed in project like mustache.hpp