Initialize from Nerfstudio

[nepfaff]

I saw that the code provides gsplat_wrapper for the gsplat rasterizer from Nerfstudio. Is it possible to use that wrapper to perform the initial vanilla 3DGS optimization with Nerfstudio?

I want to use some of the features provided by Nerfstudio, such as alpha-transparent training, which I think would work great with this method.

@Anttwo do you have any tips for getting started? I would be happy to help with writing any missing code.