The MR adds implementations (+ a few tests) for the following methods in `bluetoothapis.h`:
* `BluetoothSdpEnumAttributes` * `BluetoothSdpGetContainerElementData` * `BluetoothSdpGetElementData` * `BluetoothSdpGetAttributeValue`
-- v15: bluetoothapis/tests: Add tests for BluetoothSdpEnumAttributes and BluetoothSdpGetAttributeValue. bluetoothapis: Implement BluetoothSdpGetAttributeValue. bluetoothapis/tests: Add unit tests for BluetoothSdpGetContainerElementData and BluetoothSdpGetElementData. bluetoothapis: Implement BluetoothSdpEnumAttributes. bluetoothapis: Implement BluetoothSdpGetContainerElementData. bluetoothapis: Implement BluetoothSdpGetElementData.