[shelly] Support for CoIoT Unicast, incl. Motion 1.0.9+

[markus7017]

Shelly implemented a new feature: CoIoT Unicast (instead of Multicast)
This allows to set a dedicated IP address receiving the updates rather than broadcasting using Multicast on the local network. This is problematic when having the OH gateway and devices on different IP subnets or connected through a VPN. Using Multicast prevents the packets passing the router without special configurations. Switching to Unicast makes those packets routable.

• The Shelly Motion only supports Unicast for energy efficiency reasons. This means you HAVE TO set the COIOT PEER address in the UI
• Other devices will support this feature beginning with firmware 1.10, Unicast beside Multicast

The binding will support both modes. The user has to make sure that devices are properly configured.