macOS stores files in NFD form and transferring them like this to some
systems causes the Korean language to display incorrectly.
This adds the flag --local-unicode-normalization to optionally
normalize the file names to NFC.
This also removes the (long deprecated) --local-no-unicode-normalization flag
See: https://forum.rclone.org/t/support-for-korean-jaso-conversion/19435