fix: Ugc Add subkey for rockets and cars

[EmosewaMC]

Enables cars and rockets to actually be able to load images for their preview icons in the inventory. does not handle image generation. This will need to be handled by the end user or a 3rd party.

Tested that, if a user has followed the guide and turned UGCUSE3DSERVICES from 1 to 0, the do not get booted to login for having a rocket or a car with a subkey in their inventory; in this case, the rocket or car will never try to load an image and will always use the default.

If however, UGCUSE3DSERVICES is set to 1, the following behavior is correct as per the live client (and a sample from an old client with a rocket image).
Tested that, given a subkey of 1152921508901867691, the client expects a file called UserMade/691/01152921508901867691.dds in the UserMade folder and when a dds is placed in the folder with that name and path, the client properly renders the rocket/car with said image. (file format is last 3 digits of the subkey as the folder number and then subkey.dds).
Even if this file exists, but UGCUSE3DSERVICES is set to 0, then no images will ever be loaded, even if they exist and are correct.

[DarwinAnim8or]

I don't quite understand why this is needed? AFAIK there is no solution to generate such images at the time of writing, and IIRC simply turning UGCUSE3DSERVICES is enough to turn on the downloading of the dds from the server when done

[EmosewaMC]

I don't quite understand why this is needed? AFAIK there is no solution to generate such images at the time of writing, and IIRC simply turning UGCUSE3DSERVICES is enough to turn on the downloading of the dds from the server when done

this is how the client knows what id to actually request to be fetched. without it the client physically does not do the request anyways, regardless of the ugc being enabled or disabled.