Create sharded collections with MongoDB.Driver

PortableMongoDB.CreateShardedCollections.cs

var partitionKey = "_id";
var partition = new BsonDocument {
    {"shardCollection", $"{Database.DatabaseNamespace.DatabaseName}.{collectionName}"},
    {"key", new BsonDocument {{partitionKey, "hashed"}}}
};
var command = new BsonDocumentCommand<BsonDocument>(partition);
await Database.RunCommandAsync(command);