rgw: allow rgw-orphan-list to note when rados objects are in namespace

rgw: allow rgw-orphan-list to note when rados objects are in namespace

Currently namespaces and locators are ignored when `rados ls` is run
by rgw-orphan-list to record RADOS's known objects.

However there have been cases where RADOS objects have a locator, and
when one is included in the listing, the script does not handle it
correctly. Now when objects have locators, we will prevent their
output from entering the .intermediate file.

Additionally we do not expect RGW data objects to be in RADOS
namespaces, so when a namespaced object is detected, we'll error out
with a message.

Signed-off-by: J. Eric Ivancich <ivancich@redhat.com>