[NET-9468, NET-9902] Differentiate the ListExportedServicesQuery dependency based on the provided partition

[nathancoleman]

Prior to this change, the template below would result in printing the services exported by the default partition twice.

{{ range exportedServices `default` }}
  ...
{{ end }}

{{ range exportedServices `ap1` }}
  ...
{{ end }}

This is because the String func -- used to uniquely identify a dependency provider -- returned the same value each time and wasn't differentiated based on its arguments. Consul-template would then consider these the same dependency and return the same set of services each time.

The fix is to include the differentiator -- the partition name in this case -- in the unique identity returned by .String() for the dependency. With this change, consul-template correctly identifies the code above as having two different dependencies and thus will create a separate dependency for each partition and make the appropriate calls to Consul.

Note

For use with Consul CE, the provided partition name should be an empty string. This change will still work in that case as <Dependency>.String() will return list.exportedServices().

[DanStough]

👍