offer to trigger yum/apt install of pre-reqs if needed

[jhheider]

Running on a completely fresh ubuntu install, I needed the following:

apt install zsh libc-dev libstdc++-12-dev libgcc-12-dev libatomic1
chsh -s $(which zsh)

and to log out/in to get zshy. We should offer to run these, if we can detect what is needed.

[mxcl]

1. so, these: libc-dev libstdc++-12-dev libgcc-12-dev libatomic1

   we should provide via llvm and a libatomic pkg.

2. zsh, well we should support all shells. Specifically what required zsh?

[jonchang]

zsh, well we should support all shells. Specifically what required zsh?

I think the only bug was the one that I fixed yesterday. But there is some weirdness around shell handling still that I'm going to look into.

[mxcl]

We prompt this now.