Enhance: Optimize remotes configuration and constructor

[flycash]

What would you like to be added:

Remotes Configuration.

Why is this needed:

Now, there are many implementations based on different middleware, including zookeeper, nacos...
However, we do not have a common way to configure those middleware.
For example, If I want to use the Nacos as registry and configure center, I must configure the Nacos in two different places:

It's not convenient for users. If the user wants to change the address, he must change all places.

So I propose that we should define the RemoteConfig, it looks like:

remotes:
  nacos1:
     address: "1.1.1.1:8080"

registries:
  nacos1:
    protocol: "nacos",
    remoteRef: "nacos1",

config_center:
  protocol: "nacos"
  remoteRef: "nacos1",

[AlexStocks]

sounds good.

[zouyx]

finished