sysutils/ddiff: import package

Small utility that checks if two folders are the same.
Simple CLI binary written in Rust that computes the hash of every file inside
two different folders and look for files inside the first folder but not inside
the second folder, and viceversa, or files with matching path but different
content (hash).

Check if two folders are the same or not e.g. while copying very important
files over the network.

(pin)