Add support for newer Excel functions

Currently, Apache POI only supports old Excel functions (functions that don't have a year label here: https://support.microsoft.com/en-us/office/excel-functions-by-category-5f91f4e9-7b42-46d2-9bd1-63f26a86c0eb ) and produces wrong output with newer functions (instead of "=FUNCTION" the output is "=@FUNCTION") rendering them unusable without removing the "@" character.