Add support for listening and reconfiguring the keyboard settings from locale1

[Conan-Kudo]

Proposal

Please add support for listening and dynamically configuring keyboard settings based on org.freedesktop.locale1.

Use-cases

This is needed in order to handle cases like keyboard layout switching from the login manager (e.g. SDDM) or the installer (e.g. Calamares or Anaconda). In particular, Anaconda will require this to fully function starting in Fedora Linux 41 (see this ticket filed in the Fedora COSMIC SIG by @jkonecny12).

References

Here are a couple of example implementations for other compositors:

• KWin: https://invent.kde.org/plasma/kwin/-/merge_requests/2921
• Sway: https://github.com/alebastr/sway-systemd/blob/main/src/locale1-xkb-config