Function libmaj::app_dirs::get_app_root

pub fn get_app_root<T>(t: AppDataType, app: &T) -> Result<PathBuf, AppDirsError> where
    T: AppMeta, 

Returns (but does not create) path to app-specific data directory for provided data type.

A result of Ok means that we determined where the data SHOULD go, but it DOES NOT guarantee that the directory actually exists. (See app_root.)