Create working group for cross-cluster stateful applications

[liangyuanpeng]

Describe the issue

This is talking about create a working group to discuss and enhance the support for cross-cluster stateful applications, now, we have two user case to practical support for this work. https://github.com/xline-kv/xline is working for cross-cluster of Xline and @tpiperatgod is working for cross-cluster of zookeeper.They are all willing to contribute to this work

I'm not sure if this should be here, but I will submit a Proposal soon to create a new resource to deal with cross-cluster stateful applications.