add metadata as labels in prometheus http sd

[Kurok1]

Is your feature request related to a problem? Please describe.
Currently, in the return results of prometheus http sd, each service instance has only one default label (__meta_clusterName) returned. Can the metadata corresponding to the service instance be returned as a label?
Both Consul and Eureka are currently supported. Can Nacos also provide the same features?

目前prometheus http sd的返回结果中，每个服务实例都只有一个默认的label(__meta_clusterName)返回，能否将服务实例对应的元数据，作为label一并返回。
Consul和Eureka目前都支持，Nacos是否也可以提供相同的特性？

[Kurok1]

@i will solve it@