utils: Improve option/result types

And add the beginnings of unit tests.

lib/utils/mu-option.hh

@@ -19,8 +19,11 @@
 
 namespace Mu {
 
-/// Either a value of type T, or nothing.
+/// Either a value of type T, or None
 template <typename T> using Option=tl::optional<T>;
 
+template <typename T> Option<T> Some(T&& t) { return t; }
+constexpr auto Nothing = tl::nullopt; // 'None' is take already
+
 }
 #endif /*MU_OPTION__*/