feat: support dubbo registry rule

[gxcsoccer]

如果是 dubbo zk 注册中心，需要在 connectionString 后面加上 /dubbo/ 路径。

// 例子：（如果是集群模式，也只需要在最后加上 /dubbo/ 即可）
standalone => 127.0.0.1:2181/dubbo/
cluster => 127.0.0.1:2181,127.0.0.2:2181,127.0.0.3:2181/dubbo/

'use strict';

const logger = console;
const { ZookeeperRegistry } = require('sofa-node-rpc').registry;

const registry = new ZookeeperRegistry({
  logger,
  address: '127.0.0.1:2181/dubbo/',  // 注意：这里需要以 /dubbo/ 结尾
});

[codecov[bot]]

Codecov Report

Merging #17 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #17   +/-   ##
=======================================
  Coverage   98.42%   98.42%           
=======================================
  Files          38       38           
  Lines        1776     1776           
=======================================
  Hits         1748     1748           
  Misses         28       28

Impacted Files	Coverage Δ
lib/client/consumer.js	100% <100%> (ø)	:arrow_up:
lib/registry/zk/data_client.js	92.3% <100%> (ø)	:arrow_up:

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[gxcsoccer]

1.5.0