Support that all settings can be an "Input" (not only IInput<> types)

This is an idea to improve the usability of the Input/Output system.

Input settings will no longer have special visualizations (normally using dropdown to select an available output). Instead any setting can be assigned by the user to use the value from an output. This would probably be via a context menu.

We would keep track of settings where the user has assigned the value to an output. In DoRun() we would then set the value on that setting to the current value of that output.

We should wait until the step containing the output has finished its defer action, or possibly until it raises a new "OutputReady" event.