[Bluetooth] Add or modify uuid fields of BLE GATT objects

[Bluetooth] Add or modify uuid fields of BLE GATT objects

This commit adds uuid field to BluetoothGATTCharacteristic and
BluetoothGATTDescriptor objects and serviceUuid to BluetoothGATTService.
uuid values of BluetoothGATT{Characteristic, Descriptor} and
BluetoothGATTService::serviceUuid default to null,
if Web API implementation is unable to retrieve them from Native API.

There are more UUID fields in Bluetooth API objects, but have not been
made nullable. We expect values of BluetoothLEServiceData::uuid,
BluetoothSocket::uuid, BluetoothServiceHandler::uuid fields
to be valid, if the objects containing them are created successfully.

Related ACR: TWDAPI-255

[Verification] tct-bluetooth-tizen-tests auto: 100%;
               manual Bluetooth04_BLE_wearable: 100%

Change-Id: I4c7fe4e8b4507f07f58c0fb043081eb6d93c933c
Signed-off-by: Pawel Wasowski <p.wasowski2@samsung.com>