bug#59220: guix home does not have a way to uninstall itself

[jgart]

Hi,

guix home does not have a way to uninstall itself.

See the following resources for more context:

help-guix conversation with ludo:

https://lists.gnu.org/archive/html/help-guix/2022-08/msg00086.html

irc conversation about the bug on #tropin on Libera:

```
jgart: symlink-manager have cleanup-symlinks procedure in it, which cleanups 
dotfiles from previous generation. just declare a new home-environment with 
empty list of services and add only symlink-manager to essential-services, 
after that do a reconfigure and everything except ~/.guix-home will be cleaned 
up

abcdw_: cool! could we make a subcommand from that? guix home uninstall or 
similar.
jgart: Most people are not going to know to use cleanup-symlinks procedure in 
symlink-manager.
Thu, Sep 8 2022

abcdw joined the room
jgart: Create a proposal on bug-guix please and cc me, I'll take a look at it, 
when will get spare time
jgart: will do, thanks!
```
all best,

jgart