Add ViroFBX script support for windows/linux

[robertjcolley]

The viro docs reference this here.

[mariansam]

I ported ViroFBX to Linux in April 2021 on the ViroFBX#linux-support branch as part of my job. It definitely works on my Arch Linux machine and I'm pretty sure it will work on other Linux machines too (some dependencies might need installing).

My colleague then took my Linux port and ported it back to macOS, so it will work on both systems in one code-base. That's on the Revolware-com/ViroFBX#fix/macos-support. It works on my Arch Linux machine and generates the exact same binary (checked by sha256sum). It also auto-detects the OS during the compilation.

There are some references to Windows in the code-base, but I don't know anything more.