MB-39263: Move iterateChildren/RunObserveChildren to v2 api metakv
MB-39263: Move iterateChildren/RunObserveChildren to v2 api metakv

As part of a multi-stage process to move both of these api's to the V2
version, we are first changing all of these api's to the v2 version,
at which point we will duplicate it, without the v2 label, and then
eventually drop the v2 label in all services and finally remove the
duplicate in metakv.

Change-Id: I317774b37ef5403c4fe98368de2593eacc6f0bcd
Reviewed-on: http://review.couchbase.org/c/cbauth/+/155504
Reviewed-by: Aliaksey Artamonau <ce14b1c16e0fd654f926118eb8addbec5aff4ffa@couchbase.com>
Well-Formed: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Tested-by: Bryan McCoid <bce97493a70d35a2890d252db5140d87fb957ad5@couchbase.com>

couchbase/cbauth,couchbase/cbauth