Bug#1081798: gnome-shell-extensions: Split into separate packages

[Jeremy Bícha]

Source: gnome-shell-extensions
Version: 46.2-3

It should be possible to do any of these:
- Install the GNOME Classic mode without installing unnecessary
additional extensions
- Install only the extensions you want to use so that the extensions
list isn't cluttered
- Install the GNOME Classic session without also installing the GNOME
Classic on Xorg session, similar to what is possible by installing
gnome-session and uninstalling gnome-session-xsession

This is similar to how this is packaged in Fedora:
https://packages.fedoraproject.org/pkgs/gnome-shell-extensions/

Thank you,
Jeremy Bícha