add QueueConfiguration.JsonSerializerSettings

[tybug]

Needed the ability to specify a TypeNameHandling option when deserializing. Figure this is a good thing to have configurable anyway.

Wasn't sure if this would work better as a class-level property. Put it in QueueConfiguration for now.

[peppy]

I'd want to see the usage of TypeNameHandling before approving this direction. Generally anything but the default settings can cause security issues.