bug#47971: Improve Guix commands for update/upgrade

[Bone Baboon]

bo0od writes:
> The current commands used to make sure everything updated are not
> friendly to type nor to memorize

The name of package management commands seems like it would largely be
personal preference.

Each person using Guix could customize the commands to their own
preferences using Bash aliases or an equivalent for the shell they are
using.  For Bash refer to the Aliases section of it's info
documentation.

> - pull -> update or refresh
> - upgrade -> can be kept or package-upgrade
> - reconfigure /etc/config.scm -> dist-upgrade or distro-upgrade or
>   system-upgrade

For command names there are many package managers that you can look to
for inspiration. Here are some examples:

* Gentoo - emerge
* OpenBSD - pkg 
* Void - xbps
* Alpine - apk
* Debian - apt
* Arch - pacam or paru
* Fedora - dnf

> OR There is another approach some distros taking which is using
> shortcuts to only letters e.g
>
> pull -> p or -p
> upgrade -> u or -u
> reconfigure -> re or -re

This could also be done with shell aliases.