Feature comparison of ack, ag, git-grep, grep and ripgrep

Too bad that ugrep is missing from the comparison. I learned about ugrep via https://manueluberti.eu/posts/2022-08-07-emacs-ugrep/, which in turn learned it from https://leahneukirchen.org/blog/archive/2022/03/note-taking-in-emacs-with-howm.html