Store/containerized apps support (#4651)
* Initial containerized/Store build
* Remove unsupported APIs
* Remove usage of STL ifstream
* Revert CMake changes
* Link to app runtime
* WCOS/Store cmake
* Update CMakeSettings.json
* Fix winapi family support
* Fix downlevel
* Downlevel build
* Remove downlevel workaround
* pep8 compliance
* Workaround WinRT headers bug
https://github.com/microsoft/cppwinrt/issues/584 in older SDK
* Always cross compile to avoid warnings as errors
* PR feedback
* More CI fixes
* PR feedback
* aiinfra build fix
* Win8 store
