Legacy Skin Fix

Note: prism launcher has fixed this issue in a much better way, please use that instead, if you can.

This mod brings player textures from the new skin server to versions 1.3-1.7.5.

At the moment it only works for single player although multiplayer shouldn't be too difficult as it would just be a matter of calculating skins per ClientPlayer instead of globally, if you want that, do lmk (discord is `tildejustin`, I know, so uncreative).

please note: there is a bug in prism / multimc for versions pre-1.6 where the username and session token is not set when launching with the `noapplet` trait, which fabric loader needs to work. This is fixed in specifically these premade instances and I have a pull request to the main legacy fabric instances to add the patch to this but as of writing it is not merged. This is not an issue with the vanilla launcher.