[WIP] Cinnamon keybinding daemon

This will add the functionality necessary to allow applets, desklets and extensions to capture their own custom hotkeys, as well as add the necessary support to the settings API for enabling users to customize those hotkeys.

Finished:  autostarting daemon

Todo:  Cinnamon (gjs) api for applets, etc.. to grab keys, and a new settings type to allow users to configure hotkeys.