pipeline show: use pager instead of rendering ourselves

[efiop]

After many discussions #2420 #2768 about why our --ascii rendering is bad, I've finally remembered 🤦‍♂ that I should probably check how git does it and, lo and behold, git does use less https://github.com/git/git/blob/v2.24.0/pager.c#L8 or whatever is configured to show you things like git log instead of rendering it by itself using ncurses. We should do the same.

I'll take it. @efiop If you have any hints to make work more efficient, I'll grateful :)