Add Support for running Nintex Gateway on a cluster

A gateway cluster not only help ensure that a customer can access their on-premises data i.e. SQL from NAC but also helps avoid single point of failures when accessing the on-premise data resource. For instance, if a customer has a DR setup with two SQL server in two different datacenter locations, they will need to install Nintex Gateway on each of the servers and setup two different connections in NAC. In the event of a failure on either one of the SQL nodes, they will have to intervene and manually change the connection in NAC. And, depending on when or how quickly the customer discovers the failure, can significantly impact their inflight business processes.

With cluster support, incoming requests are routed to the primary gateway node in the cluster. And, if the primary gateway node isn't available or reachable, the request is routed to next gateway node in the cluster, and so on. This helps mitigate the need for a manual innervation in NAC.