* archive: Make use of std::pair for OpenFileFromArchive
The tuple only makes use of two elements, so we can use a pair to
simplify the number of underlying template instantiations that need to
be done, while also simplifying the surrounding code.
* archive: Simplify MakeResult calls
MakeResult can deduce the contained result type based off the type of
the variable being passed to it, so explicitly specifying it is a little
verbose.
f7aaa37bf2