Rename COPY option from SAVE_ERROR_TO to ON_ERROR
The option names now are "stop" (default) and "ignore". The future options
could be "file 'filename.log'" and "table 'tablename'".
Discussion: https://postgr.es/m/
20240117.164859.
2242646601795501168.horikyota.ntt%40gmail.com
Author: Jian He
Reviewed-by: Atsushi Torikoshi