add openSUSE Tumbleweed style btrfs + snapper + rollback support in the Debian installer

[Anchal Nigam <imthenachoman@gmail.com>]

One of the really cool things with the openSUSE Installer is it lets you configure btrfs and snapper right from the installer. This results in two things:

1. Every time you install something using `zypper` it automatically takes a pre/post snapshot

2. You can boot into a snapshot right from grub and restore it

This is a pretty powerful feature.

https://github.com/david-cortes/snapper-in-debian-guide is a guide on how to do this with Debian. Once it's setup, it'll automatically take pre/post snapshots when you run `apt` and you can boot them from grub. It's great.

I am wondering if the Debian developers would consider adding this into the Debian installer so it's easier to configure/setup/enable.

I really feel this is a huge value-add ability and I think it would benefit the Debian user-base to have this available in the installer.

-- 
Thank you!
_Nacho

(He/Him/His)