Support Nacos as a configuration source for vertx-config

[qianwj]

Describe the feature

Description:
Currently, vertx-config supports multiple configuration sources (e.g., file, JSON, Git, Consul, etc.), but it does not support [Nacos](https://nacos.io/) as a configuration center.
Nacos is widely used in many environments, especially within the Spring Cloud ecosystem. Supporting it as a ConfigStore implementation would allow Vert.x applications to integrate seamlessly with existing Nacos-based configuration infrastructures.

Proposal:

• Add a new NacosConfigStore implementation.

• Use the official Nacos Java SDK to fetch configuration data.

• Support configuration change listeners to enable dynamic updates (similar to the ConsulConfigStore).

• Example configuration:

  {
    "type": "nacos",
    "config": {
      "serverAddress": "127.0.0.1:8848",
      "namespace": "public",
      "dataId": "app-config",
      "group": "DEFAULT_GROUP"
    }
  }

Motivation:
Adding Nacos support would improve Vert.x’s compatibility with widely adopted configuration systems in the Chinese and cloud-native developer communities. It would reduce the need for custom bridge layers and simplify configuration management.

References:

• [Vert.x Config Documentation](https://vertx.io/docs/vertx-config/java/)
• [Nacos GitHub Repository](https://github.com/alibaba/nacos)

Contribution

I’m willing to implement this feature and contribute a pull request once the idea is approved.