Blender Git Loki

Merge branch 'master' into temp-cpp-file-system

Merge branch 'master' into temp-cpp-file-system

Fix compile errors on Windows

Remove wrong changes

Windows: Undefine options for Windows.h after use

Fix compile errors with `USE_CPP_FILESYSTEM` disabled

Initial work for std::filesystem transition

* Add ghc::filesystem as platform compatible replacement for
std::filesystem
* Add Windows specific code to avoid issues with including Windows.h
* Port storage.cc to C++
* Port some functions from storage.cc to use ghc::filesystem internally.
* General cleanup related to the changes.
* Add USE_CPP_FILESYSTEM compile option to storage.cc, to keep legacy
code around for testing.