Allow to specify a path for the server provided assets.

[Jupeyy]

For now in config dir only:

Allows mods to specify an asset, like skin, with a name + hash to force the client to load exactly that asset (triggering the download from game server instead of the assets server).

// info here is the player info, like name, skin etc.
info.skin = ResourceKeyBase {
    name: "default".try_into().unwrap(),
    hash: decode_hash(
        "eca1544ddc97c33db47e2543ae0ff42b7f6909860dc8dad039887101dbc72d09",
    ),
}
.try_into()
.unwrap();