NVIDIA GameWorks Integration

It’s stable, but the integration should have gone on top of 4.8.1, but I wasn’t careful enough when I did it and I merged it onto the head revision, which is 4.8.2. After inspecting the changelists more closely, I realize that I accidentally changed some completely unrelated engine code, reverting it to 4.8.1 (navigation mesh code, some editor code), so I need to fix before I merge to the VXGI branch. The VXGI-dev branch is indeed stable, but be careful if you merge it to a 4.8.2 branch because it may overwrite some of the 4.8.2 changes.