Implement night shadows

[mchaptel]

In order to render the shadows at night, we need to grab the moon coordinates.

This is an example of how to do that in New Vegas:

https://github.com/jazzisparis/JIP-LN-NVSE/blob/main/nvse/GameData.h#L323
https://github.com/jazzisparis/JIP-LN-NVSE/blob/main/nvse/GameData.h#L387

https://github.com/WallSoGB/MoonlightNVSE/blob/main/MoonlightNVSE/main.cpp#L244

[mchaptel]

added thanks to @mcstfuerson

mchaptel@37c31fa

Should I cherry pick this commit onto a branch on the repo? Maybe make a PR with it?