Proposal: abstract base registry

[hxmhlt]

What would you like to be added:
Refactor the registry/ and remoting/ code in dubbogo. To abstract the same logic into common code.

Why is this needed:
At present, there are too many duplicate codes in the implementation of ZK, etcd, Nacos, k8s and other registries. And because we haven't abstracted the common code, the extension of registry has to write a lot of control logic.

[hxmhlt]

Done.