OneTimeOverrides

Some override files, such as `options.txt`, should only be copied the first time a player plays a modpack. Otherwise, their changes would be lost every time the modpack is updated.

This mod allows modpack authors to place files in the `one-time-overrides` directory that will only be copied to their intended destination if the target file does not exist.

Example: ``` .minecraft ├── config │ └── first_mod.toml └── one-time-overrides │ └── config │ └── first_mod.toml # already exists in .minecraft/config -> will not be copied └── options.txt # does not exist in .minecraft -> will be copied ```

As it does not use any Minecraft-specific APIs, the mod should work with any version of the game. `1.18.2` and `1.19.2` were tested.

The only dependency is fabric-language-kotlin. Fabric API is not required.