common: Implement a subset of P0323 (std::expected)

This implementation is based on and is a subset of the proposed implementation of std::expected
https://github.com/TartanLlama/expected/blob/master/include/tl/expected.hpp

src/common/CMakeLists.txt

@@ -55,6 +55,7 @@ add_library(common STATIC
     dynamic_library.h
     error.cpp
     error.h
+    expected.h
     fiber.cpp
     fiber.h
     fs/file.cpp