A utility method for cleaning up expired sessions that IIS failed to delete. The method performs a scan on the table
with a condition that the expiration date is in the past and calls delete on all the keys returned. Scans can be costly on performance
so use this method sparingly like a nightly or weekly clean job.

C# |
public static void DeleteExpiredSessions( AmazonDynamoDB dbClient, string tableName )

- dbClient (AmazonDynamoDB)
- The AmazonDynamoDB client used to find a delete expired sessions.
- tableName (String)
- The table to search.