Pre-build system configurations before running Terraform/Packer deployments

[matthewmazzanti]

System builds happen mid-process, so any nix errors will only show up after remote instances are started. This slows things down and costs money (not much, but more than zero). We should be able to pre-run the nix build and abort the terraform portion of it fails.

I have not been able to actually pre-build for deploy-rs though. Trying to build nix build .#deploy.nodes.tailscale.profiles.system.path seems to re-run the build. (Needs more triage)