get with prefix

[texnicii]

Added request with prefix which returns Generator<Mvccpb\KeyValue>

// example 
foreach ($client->getWithPrefix('/some-namespace') as $val) {
    echo $val->getKey() . " -> " . $val->getValue() . "\n";
}

[CLAassistant]

All committers have signed the CLA.

[matthi4s]

Thanks for the pull request! You haven't updated the ShardedClient yet, but with the changed ClientInterface, that would cause fatal errors. You probably have to request all keys from all clients for the ShardedClient.