gs-details-page: Addons section can show addons for a different app

When the app changes during the initial load, the addons section could
still show the previous app's addons. Let the whole Addons section
be updated inside the refresh_all(), rather than just show/hide it.
Similarly cover reviews on the app change during the initial load.

(Rebase gnome-41: Minor rebase conflicts.)

Closes https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1526