Add winrt buildscripts

Add a few Dockerfile:

• 2 toolchain Dockerfile's, which are required to build the proper compiler for a WACK friendly WinRT build, plus libwinstorecompat with a few patches.
• 4 config branches

There's probably room for improvement, especially on the config side... So far, we simply run the winrt compile.sh script, which means a single layer will clone + build the contribs + build vlc + package the build This is ok-ish when everything works fine, though we might not want to rebuild all contribs each time we want to produce a build.

This might be a safer approach for now though, as the build still arent fully validated by the WACK. It's highly likely we will also have to rebuild the toolchain images.