ports tree bootstrap using git

From: Jonathan Reynolds <jreynolds1729_at_gmail.com>
Date: Sun, 09 Apr 2023 11:43:43 UTC
I created a program that downloads the required files from
https://cgit.freebsd.org/ports/plain/ to build and install
devel/git. It then uses the newly installed git to clone
the ports tree from https://git.freebsd.org/ports.git

I opened a review at https://reviews.freebsd.org/D39472
and seeking for reviewers.