[Feature Request] Basic "sensor-like" support for home appliances
As you clearly stated, this updated plugin does not support home appliances as Homekit does not natively supports that. Cannot complaiun about that :) 

As a feature request, I would ask to get a basic sensor like behavior for just ON/OFF of the home appliance. This, in turn, can at least provide a basic capability of knowing when an appliance is done, like the washer and/or dryer have completed their cycle.

From the Homebridge logs I added below your plugin clearly receives the events from the appliances so I assume a receiving Virtual Homekit ON/OFF Sensor could be tied to these events. If you need more event info I am happy to provide them and obviously test a potential implementation.

Example events from Homebridge log for starting the dryer:
```
[2/28/2020, 10:53:04 am] [SmartThings-v2] INFO: [Device Event]: (Dryer) [DRYERJOBSTATE] is drying
[2/28/2020, 10:53:04 am] [SmartThings-v2] INFO: [Device Event]: (Dryer) [TIMESTRING] is 00:48:00 Remaining
[2/28/2020, 10:53:04 am] [SmartThings-v2] INFO: [Device Event]: (Dryer) [COMPLETIONTIME] is 2020-02-28T16:41:03.947Z
[2/28/2020, 10:53:04 am] [SmartThings-v2] INFO: [Device Event]: (Dryer) [MACHINESTATE] is run
```
In the logs I can clearly see that it polls the appliance every minute (sample of polling events):
```
[2/28/2020, 12:17:02 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [COMPLETIONTIME] is 2020-02-28T17:36:02.206Z
[2/28/2020, 12:17:02 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [TIMESTRING] is 00:19:00 Remaining`
```
These are the completion events of the job:
```
[2/28/2020, 1:21:49 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [COMPLETIONTIME] is 2020-02-28T18:21:49.311Z
[2/28/2020, 1:21:49 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [DRYERJOBSTATE] is finished
[2/28/2020, 1:22:19 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [DRYERJOBSTATE] is none
[2/28/2020, 1:22:20 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [COMPLETIONTIME] is 2020-02-28T19:37:19.918Z
[2/28/2020, 1:22:20 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [TIMESTRING] is 01:15:00 Remaining
[2/28/2020, 1:22:20 pm] [SmartThings-v2] INFO: [Device Event]: (Dryer) [MACHINESTATE] is stop
```
Perhaps using the [MACHINESTATE] run/stop events is a simple and generic enough mechanism for an ON/OFF state?

This would be an awesome addition to an already awesome plugin!
Appreciate the consideration!!!