[Enhancement] Refactor Methods for v6.0.x

[DamianSuess]

Refactoring:

• Rename Device.GetAllAsync() to ..GetPropertiesAsync()
• Rename Device.GetUUIDsAsync() to ..GetServiceUuidsAsync()
• Include DeviceExtensions as part of Device class
• Rename Device.GetConnectedAsync() to IsConnectedAsync()

Normalization:

• Use custom Interfaces versus BlueZ dependent ones