Expand on Multi-Cluster Environment

[dastergon]

Due to the masterless architecture of Ansible, TC Panel cannot operate on a multi-cluster setting where the clusters are located in different physical regions and multiple CIDR blocks. The hosts may live behind a NAT and only a single IP will be shown to the application. Since it does not keep state, it is not feasible to identify the topology behind it. Using a service discovery solution can resolve that issue by maintaining the state of all internal hosts in the different regions. The trade-off of this decision is that it brings extra overhead to the manageability and maintainability of the whole setting.