Standalone client doesn't work with itools

[jonenst]

• Do you want to request a feature or report a bug?
  bug

• What is the current behavior?
  hard to use itools to do something with network-store

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem
  itools convert-network --input-file a.xiidm --output-file b.xiidm --output-format XIIDM

with the following config.yml

network:
    default-impl-name: NetworkStore

• What is the expected behavior?
  works

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. stackoverflow, spectrum, etc)
  To fix it, I had to :

• use network-store-client, instead of network-store-iidm-impl because some extensions are in the client
• add a NetworkFactoryService class:

package com.powsybl.network.store.iidm.impl;
import com.google.auto.service.AutoService;
import com.powsybl.iidm.network.NetworkFactory;
import com.powsybl.iidm.network.NetworkFactoryService;

@AutoService(NetworkFactoryService.class)
public class NetworkFactoryServiceImpl implements NetworkFactoryService {

    @Override
    public String getName() {
        return "NetworkStore";
    }

    @Override
    public NetworkFactory createNetworkFactory() {
        return new NetworkFactoryImpl();
    }
}