Increase configurability for ~/.config and ~/.local paths

[msanft]

Hey there!

The PR NixOS/nixpkgs#302417 tries to package Supermodel for NixOS. Nix Packages have to strictly live in one path only, which is why programs relying on external directories (e.g. ~/.local/share/supermodel/Assets/ and ~/.config/supermodel/Config/Supermodel.ini for Supermodel) are usually wrapped with command line arguments specifying different paths for such values. This does not seem to be possible with Supermodel currently.

Would it be possible to make the path to the ~/.local/share/supermodel and ~/.config/supermodel/ directories configurable via the command line?

Thanks in advance!