Opening docs via asp notification result in a browser lacking AT-SPI access

I.e. the browser opening the docs doesn’t support the screen reader, and cannot be seen by Dogtail so automated testing is requires workarounds.

It can easily be reproduced with:

python3 -c "import importlib; importlib.machinery.SourceFileLoader('m', '/usr/local/sbin/tails-additional-software').load_module()._notify('', documentation_target='about')"

(We just import /usr/local/sbin/tails-additional-software as a package, and run its _notify() method.)

Clicking the “Documentation” action button results in this exact call:

sudo -u amnesia /usr/local/lib/tails-additional-software-notify '' '' '' '' 'about' ''

Indeed, if I run that command myself, the resulting browser lacks access to AT-SPI. But if I drop the sudo part and run it directly as amnesia it works fine. Comparing to how we solved this problem in /usr/local/sbin/tails-notify-user, I bet what is missing is the Python equivalent of:

source /usr/local/lib/tails-shell-library/gnome.sh && export_gnome_env

Feature Branch: tails: bugfix/16475-asp-notifications-gnome-env submodules/pythonlib: bugfix/16475-asp-notifications-gnome-env

Parent Task: #14568 (closed)

Original created by @anonym on 16475 (Redmine)