Get input state
**Describe your problem**
I would like to know if there is a way (using any device type config) to read the 'input' pin of a Shelly 1 or Shelly Uni device. I mean to read the current state of the INPUT pin (also named switch input) not the relay state (or output).
As far as I see the read state is alway the relay state.
I am using the relay output decoupled of its "switch input", so reading the relay state is not valid for me.

**Describe what you have tried so far**
I tried several device types. I thought that perhaps, using specific configuration setting "contact sensor" as device type, the device would show the state of its input (not the relay input). Unfortunately relay state is always shown, and it seems there is no way get the "switch input" state.

**Environment:**
 - Shelly device(s): Shelly 1 and Shelly Uni
 - Plugin version: v0.19.1
 - Device running homebridge: Raspberry Pi

Great plugin anyway. Kind regards
