[Feature Request] Keybind to toggle "auto tiling" on and off

Hi @domferr thank you so much for the awesome extension! I have a request/suggestion related to the recently introduced (https://github.com/domferr/tilingshell/issues/169) auto tiling.

Most of the time auto tiling is what I want out of my window manager, but depending on what I'm working on I sometimes don't want it. My specific use case is that I am developing a desktop application that closes and re-spawns its main window as I make changes in the source code and it is helpful if the application window always spawns into the same position and size every time (based on the configuration in my code).

I find myself manually going into the `tiling-shell` extension settings to toggle "auto tiling" off while I'm working on my desktop application, and then going back in and toggling "auto tiling" back on when I am using my computer for non-development work.

It would be great if I could just hit a configurable keybind rather than having to open up the gnome extension settings to toggle this setting.

Thanks for considering, cheers!