Validate all events have the correlation ID

[bongiovimatthew-microsoft]

The following TODO item exists in the code:

function: Process-EventsForAnalysis

TODO: Validate that all events have the same correlation ID, or no correlation ID

When we do the first pass through the events to build the hashtable of instance IDs, we should validate the correlation IDs

Put up a warning if we ever see an event with a different correlation ID (it's okay for it to have no correlation ID)