Add support for setting up data plane backup node as part of kong helm chart

[shambhand]

https://docs.konghq.com/gateway/latest/kong-enterprise/cp-outage-handling/

We do not recommend using backup nodes to proxy traffic. The backup job enlarges the attack surface of a proxying DP and contributes significantly to the P99 delay. You need to know the risk if you want to deploy a node this way, and the DP needs to be at least 3.6.0.0 to be provisioned with backup configuration when it’s configured as a backup node. Although a single backup node is sufficient for all deployments, you can also configure additional backup nodes. A leader election algorithm selects one node from the group of designated backup nodes to do the backup job.

If there is requirement or strong recommendation for having dedicated backup node separated from the actual data plane node.

Can we have the same kong helm chart to support the separate backup node along with the actual data plane node install?