Add back the ability to toggle models

Earlier it was possible to toggle models on and off, this feature is removed. Adding a keybinding manually to aiSettings.action.toggleModel does not work.

It would be great to be able to toggle models on and off, either as a setting or via keybindings so that it is more useful to toggle models with cmd+/.

This is especially important now that Composer mode is gone, and we’re having one single model for both Ask, Edit and Agent, since we now have to change the model manually between the modes.