Create additional tests to cover regressions that were discovered by PRs linked to D10098, D10102, and D10104.
It is worth noting that neither bsdgrep(1) nor gnugrep(1) in the base system currently pass all of these tests, and gnugrep(1) not quite being up to snuff was also noted in at least one of the PRs.
Additionally, I have no idea how this should be reconciled with upstream. I don't know what their current status is, but I assume they're in the same boat as us as far as grep(1) goes.