emitting event to synchronize GUI with plugin state

[owengc]

Opening an issue for this so we remember to discuss it further in the near future

GUI's that sync state via event listeners need a signal to indicate that the plugin's state has changed due to setParameterValues or setState.

I've worked around this for now by converting the state update into a series of emitted wam-automation events. This works but isn't necessarily appropriate for all such GUI syncing tasks, and it feels kinda hacky. Instead, we could introduce a wam-state or wam-gui event type which would be emitted by the plugin to notify the GUI that it should update according to whatever internal state changes have occured (which may not be limited to parameter values).

An argument against this would be that devs are already free to emit whatever custom events they wish, so we don't necessarily need to put this into the API. On the other hand, if we did have a wam-state event, we could potentially support scheduling preset changes via scheduleEvents, which would be kind of cool.