fix: healthcheck manager missing runtime information

[Revolyssup]

• In case of service discovery, the node_ver information is not attached to the service received from etcd (due to deepcopy) therefore it's lost and healthchecker is not recreated.
• In case of dns, dns_value is not attached to the data from etcd for similar reason.

Solution:

• Since we use the data from etcd in healthcheck, we need the runtime information like nodes_ver and dns_value to be stored. This PR refactors the code so that those runtime updated values are persisted for future requests via healthcheck module.

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[membphis]

in my opinion:

create a new module, it's name can be resource

then we can use it by call core.resource.get_nodes_ver, what do you think? @Revolyssup

[Revolyssup]

done

[membphis]

move this function to upstream lua module

[Revolyssup]

done. moved to utils/upstream

[membphis]

LGTM