[Enhancement] Refactor Methods for v6.0.x

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