Function load_cascading_project_config_fs 

pub fn load_cascading_project_config_fs<F: FileSystem>(
    fs: &F,
    project_root: &Path,
    ito_path: &Path,
    ctx: &ConfigContext,
) -> CascadingProjectConfig

Configuration loading and schema helpers. Like load_cascading_project_config, but uses an injected file-system.