[Engine] Support Dynamic Network Re-configuration

The current release version or the version from the master branch does not support reconfiguration. The number of replicas to be deployed is determined by the configuration when deploying to the cluster.

We need to support adding and removing replicas when resilientDB is running in the cluster after deployment.

The issue identifies the Engine and resilientDB's cluster deployment configuration as the starting context; inspect how the configured replica count is applied when the cluster is deployed. The work is complete when replicas can be added and removed while resilientDB is running, rather than only being fixed at deployment.

Written by the indexing model from the issue text.