[shelly] Add BLU Gateway and range extender support for Plus RGBW PM #19252
Description
Expected Behavior
As Shelly Plus device, RGBW PM (shellyplusrgbwpm) should also have a configuration item in the thing that allows to enable the BLU Gateway.
Current Behavior
The BLU Gateway activation configuration is missing in Thing configuration - althoug the device supports it as "plus" device
