Get commonlibsse-ng into Microsoft's vcpkg repository.

[jpstewart]

This is a bit of an up-in-the-air idea for a couple of reasons. First, practically, Vcpkg has no options feature, so it requires upstreaming at multiple packages (commonlibsse-ng is the requirement, but possible commonlibsse-ng-flatrim and commonlibsse-ng-vr as additional baseline requirements). Secondly, since the upstream already uses Vcpkg, it feels rude to push this into the upstream Vcpkg repo without the upstreams being there.

Nevertheless keep an I on this, as it simplifies consumption significantly.