[ISSUE #3904] feature - operate instance's metadata alonely

[horizonzy]

What is the purpose of the change

#3904

[KomachiSion]

@horizonzy I think the API can be move to InstanceController
@chuntaojun What's your think about?

[horizonzy]

@horizonzy I think the API can be move to InstanceController

it should be move to InstanceController

[horizonzy]

update demo:
curl -X PUT 'http://localhost:8848/nacos/v1/ns/instance/metadata/batch?namespaceId=public' -d 'metadata={"age":"20","name":"cocolan"}&namespace=public&serviceName=xxxx@@xxxx&instances=[{"ip":"3.3.3.3","port": "8080","ephemeral":"true","clusterName":"xxxx-cluster"},{"ip":"2.2.2.2","port":"8080","ephemeral":"true","clusterName":"xxxx-cluster"}]'
or
curl -X PUT 'http://localhost:8848/nacos/v1/ns/instance/metadata/batch?namespaceId=public' -d 'metadata={"age":"20","name":"cocolan"}&namespace=public&serviceName=xxxx@@xxxx&consistencyType=ephemeral'

the result:
{"updated":["2.2.2.2:8080:unknown:xxxx-cluster:ephemeral","3.3.3.3:8080:unknown:xxxx-cluster:ephemeral"]}

[horizonzy]

delete demo:
curl -X DELETE 'http://localhost:8848/nacos/v1/ns/instance/metadata/batch?namespaceId=public' -d 'metadata={"age":"20","name":"cocolan"}&namespace=public&serviceName=xxxx@@xxxx&instances=[{"ip":"3.3.3.3","port": "8080","ephemeral":"true","clusterName":"xxxx-cluster"},{"ip":"2.2.2.2","port":"8080","ephemeral":"true","clusterName":"xxxx-cluster"}]'
or
curl -X DELETE 'http://localhost:8848/nacos/v1/ns/instance/metadata/batch?namespaceId=public' -d 'metadata={"age":"20","name":"cocolan"}&namespace=public&serviceName=xxxx@@xxxx&consistencyType=ephemeral'

the result:
{"updated":["2.2.2.2:8080:unknown:xxxx-cluster:ephemeral","3.3.3.3:8080:unknown:xxxx-cluster:ephemeral"]}

[chuntaojun]

最后补一个集成测试吧，总体应该可以先merge

[KomachiSion]

@horizonzy Can you update documents in https://github.com/nacos-group/nacos-group.github.io?

[horizonzy]

https://github.com/nacos-group/nacos-group.github.io

yes