Now that we have support for extension updates in the shell, we
need some place to display the updates to the user.
As we are establishing the Extensions app as the primary way for
managing extensions, it's a natural place for that functionality.
Show which extensions have updates available, and offer a log out
button (so gnome-shell can apply the updates when logging back in).
https://gitlab.gnome.org/GNOME/gnome-shell/issues/1968
The description can be useful information, but also increases the
visual complexity of the extensions list. Move it into a hidden
details area that can be expanded, which unclutters the interface
while keeping the information readily available.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/1968
