Dynamic lang pack installation support

• debian/patches/Dynamic-lang-pack-installation-support.patch
  • Adding a polkit rule to allow the gnome initial setup user to run pkexec if the program it is running is apt
  • Adding a function apt_get_install that takes in a list of packages and attempts to install them.
  • Added parse_language_list function to parse the static list of languages in /usr/share/language-selector/data/languagelist which is now used to populate the language chooser.
  • Added the ability for GIS to determine what outstanding language packs need to be installed via check-language-support -l and to use that output to install outstanding lang packs via a g_task.
  • Added a spinner to the language chooser for when a language has been selected and packs are being installed

This is my first time really making use of glib, so I am not sure if there are better ways of calling the sub-processes / if I am handling the g_task spawning correctly.

I am getting a strange delay on 24.10 where pkexec being called sits at 100% cpu usage for several minutes before any logs appear that indicate its actually running the apt-get commands. Once they appear in the logs they finish in the expected time frame.

I see Seb added the translations from LP in launchpad_translations_export.patch, but I am not sure if there is anything in addition to setting the locale I need to do to make use of them?

Spec is available here: https://docs.google.com/document/d/1gp94PPVePl06yyEfBIyQ4ASL4aduB_Gbp1phPCNi5cE/edit?usp=sharing