Shelly HomeKit FW 2.1.7

• Ability to assign individual switches to different rooms (note: you may need to remove and re-add the accessory to the home).
• Ability to operate input pins as independent stateless switches - set input mode to "detached" and it will appear as its own accessory.
• Code rewritten almost completely to support easier development in the future.

Note: Sometimes accessory settings are lost after the upgrade, you may need to reconfigure the accessory in the Home app.

If updating multiple devices, try a script: tools/flash_shelly.sh -a
Thanks @andyblac for contributing it!