deskutils/rednotebook: new port

RedNotebook is a modern desktop journal. It lets you format, tag, and search
your entries. You can also add pictures, links, and customizable templates,
spell check your notes, and export to plain text, HTML, LaTeX, or PDF.

PR: 276963
Author: Travis Hunter <cth-freebsd@pm.me>
Reviewed-by: arrowd, henrichhartzer@tuta.io