Update XMP IPTC tags to 2021.1 standard

Changes:
1. Add/update tags.
2. According to the standard, several tags in
   `Xmp.iptc.<property>` and `Xmp.iptcExt.<property>`, had been
   wrongly added, as they only exist as part of a struct used by a
   tag. The incorrect tags have been marked as deprecated in the
   label and description.
3. Update existing test with translated output.

Ref: [IPTC Photo Metadata Standard 2021.1](https://www.iptc.org/std/photometadata/specification/IPTC-PhotoMetadata-2021.1.html)

Author: postscript-dev