Add timestamp for zwave_js.value_updated trigger to support mode: queued

I’m tracking Z-Wave events (reports) to differentiate local on/off and single-tap. These events can arrive with 15ms timing. A zwave_js.value_updated trigger does not have a timestamp under the trigger variable. This means I have to use mode: parallel and rely on the automation’s shared .attributes.last_triggered. It’s not always possible to complete processing in 15ms. I’ve front-loaded the time-critical logic, but I can see that my log messages are sometimes preempted by the next Z-Wave event. I would prefer to use mode: queued. That would only be possible if each event has its own timestamp for post-processing.