[Ekapkgs] Create TUI for minimal install

[jonringer]

For the vast majority of simple installs, the steps are usually:

• Format/partition disk (if needed)
  • ask: FS type (ext4, zfs, btrfs, etc)
  • ask: Swap y/n? If yes, how much?
  • ask: Encrypted?
  • (could probably just serialize this into a disko config)
• Mount partitioned disk at /mnt
• Generate a reasonable /mnt/etc/nixos/configuration.nix (can be overwritten later)
  • DE/WM preference could be asked
• run nixos-rebuild boot (eventually ekaos-rebuild)
• Set root password

There's not a lot of decision making being done, and a lot of these options can be shown to the user in a much easier manner than remember commands like fdisk -l to explore block devices, and then run a fair number of a partition and installing commands which are kind of "known ahead of time".

[sshine]

The graphical NixOS installer has consistently failed me when checking FDE (full disk encryption).

I think this is an area that is somewhat essential, and also the space of combinations is rather large.

For example, LUKS inside LVM, LVM inside LUKS, ZFS providing its own encryption.

As a starting point, a TUI could provide limited options being simply "FDE y/n?"

[jonringer]

Disko supports something like this: https://github.com/nix-community/disko/blob/master/example/luks-lvm.nix

And I've been happy with it's behavior so far.