Add actions as a first-order object, rather than an implementation detail of user-interaction animations (`pick`/`knob` etc), input configurations, and UI bindings. Actions are essentially a named binding, with some extra information + state: 1. can be enabled / disabled 2. have a unique identifier 3. Can be replaced, optionally (so aircraft can redefine what a standard action such 'toggle active COM frequency' does in their cockpit) 5. can have UI prompts (description / tooltip text) This feature is targeted for `next`, but could potentially be back-ported, since it needs to be done backwards compatibly anyway.