Change how BluetoothAdapter identifies devices

[tthiery]

• Abstract identity in an interface independent of Mac Address
• Change PoweredUpHost function to use generic state instead
  of bluetooth address as ulong
• Implement interface in existing adapters (simple transformation)
• Change BluetoothKernel interface to accept device instead of
  bluetooth address
• Add formatting to the MAC Address DeviceInfo

Closes #154

[Berdsen]

Hi @tthiery,
unfortunately I had not enough time but today I took this changes and improved them, so that I could establish a working connection also with iOS devices.
I'm not done with the implementation but you can see the current code I made on your base here:
https://github.com/sharpbrick/powered-up/compare/issue-154-deviceinfo...Berdsen:issue-154-deviceinfo-adjustements?expand=1

So the iOS solution will get a GUID as DeviceIdentifier (NSUuid) whereas the Android DeviceIdentifier will be the MacAdress as string :)

Works at least for both implementations, so we can go for this for now.

As an example with ExampleBluetoothByKnownAdress I have to give the NSUuid as string and it will also work. I need to check how this will work ExmpleTwoHubsMotorControl I have to check, if it is also working, when I know the UID.