feat: enhance observability with plugin (#3)

[shunjiazhu]

增加add veadk observability plugin
用法:

在配置文件中添加observability配置

observability:
  opentelemetry:
    apmplus:
      endpoint: "https://apmplus-cn-beijing.volces.com:4318"
      api_key: "YOUR_APMPLUS_API_KEY"
      service_name: "YOUR_SERVICE_NAME"

在代码中引入plugin：

  config := &launcher.Config{
      AgentLoader:    agent.NewSingleLoader(a),
      PluginConfig: runner.PluginConfig{
          Plugins: []*plugin.Plugin{observability.NewPlugin()},
      },
  }