tails-greeter: localize keyboard layout names

Seems like all the UI’s l10n is correctly updated on language change, but the keyboard layout widget is constantly displayed using the locale the window was loaded with.

in ubiquity, the d-i/make-keyboard-names script uses /usr/share/locale/*/LC_MESSAGES/xkeyboard-config.mo to translate the keyboard layout names, from list of keyboard layouts gathered using the d-i’s console-setup Keyboard/KeyboardNames.pl script
kbd-chooser.c in git://git.debian.org/d-i/kbd-chooser.git uses /usr/share/console/lists/

Feature Branch: feature/localized_layouts

Related issues

Has duplicate #16442 (closed)

Original created by @tails on 6084 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information