Get the global hotkeys working

[Vadoola]

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[Vadoola]

Initial support for this was added in commit c6a2fbd.

I'm leaving this open for now, because it needs to be tested on Linux / X11, and if possible MacOS.

Also until tauri-apps/global-hotkey#28 is resolved, it won't work under Wayland.

In addition the hot key commands can't be customized and are locked to Control+F1, Control+F2, and Control+F3 currently.

[Vadoola]

I have started a discussion on the Slint project, about how to handle determining which function key is pressed using FocusScope: slint-ui/slint#4401

[Vadoola]

Commit 9f31a1c, added support for saving and restoring the global hotkeys to the settings file.

Still some more work to do

• actually update the hotkey when I change the hotkey setting (right now its set to the default Ctrl-Fx keys at start up and doesn't change)
• add logic to check if the hotkey is already used and reject it (either because its already assigned to another hotkey in Tomotroid or elsewhere)