[FEATURE] Generic "do nothing" command for non stateless switches
### Feature request...

A `DoNothing` command that can be passed on either side of the `/` (for _non stateless_ switches) when publishing devices.

### Config (example)...

`Logitech Amp|Optical;InputOptical/DoNothing`
`Logitech Amp|Coax;InputCoax/DoNothing`
`Logitech Amp|Direct;InputDirect/DoNothing`

### Results...

- When a switch is turned **On**, it will pass the associated command.
- When a switch is turned **Off**, it will essentially do nothing.

This allows for a _non stateless_ switch that does not require a command for both **On** and **Off**.  Specifically, in this scenario, a _non stateless_ switch can be turned **Off** without passing the same (or any) command.

### Automation benefits (example)...

Home App:

- When Optical is turned **On**, turn **Off** Coax and Direct.
- When Coax is turned **On**, turn **Off** Optical and Direct.
- When Direct is turned **On**, turn **Off** Optical and Coax.

### Additional context...

Currently, a _non stateless_ switch requires (and passes) a command on both sides of the `/`.

The problem with this—when attempting the scenario (automation) above—is that undesired input commands are sent (when switches are turned **Off**) along with the desired input command (when a switch is turned **On**).

Specifically, one of the other two inputs is activated, instead of the desired input.

Having a generic "do nothing" command would solve this issue.