Support for custom serialization providers

[dvera-phs]

This change adds support for using custom serialization providers in the communication between ServiceFabric services. I've tested this change using Microsoft's sample JSON SerializationProvider, but any provider should be able to be passed in when the service is created at startup. Identical custom serializers will need to be passed into both the client facing service and the internal service.

For example, when using the JSON Serializer in ClientApp and DistributedCacheStore, we'd do the following to register the SerializationProvider:

ClientApp/Startup.cs

services.Configure<ServiceFabricCacheOptions>(o => {
    o.RetryTimeout = TimeSpan.FromSeconds(5);
    o.SerializationProvider = new ServiceRemotingJsonSerializationProvider();
  });

DistributedCacheStore/DistributedCacheStore.cs

public DistributedCacheStore(StatefulServiceContext context)
   : base(context, (message) => ServiceEventSource.Current.ServiceMessage(context, message), serializationProvider: new ServiceRemotingJsonSerializationProvider())
 { }