Azure Blob storage provider has fixed json extension

[EdoardoTona]

The Azure Blob storage provider (AzureBlobGrainStorage) has fixed .json extension in the blob name:

orleans/src/Azure/Orleans.Persistence.AzureStorage/Providers/Storage/AzureBlobStorage.cs

Line 135 in 2d21b3f

private static string GetBlobName(string grainType, GrainId grainId) => $"{grainType}-{grainId}.json";

Since the grain storage serializer can be customized (e.g. using the new binary Orleans Serializer), it would be nice to be able to configure the blob file extension from json to something else (including empty string = no extension).