rgw: filter fetch remote obj after reading remote metadata

rgw: filter fetch remote obj after reading remote metadata

In the sync case: find the appropriate pipe params that match this
remote object (if matches tags / prefix), and adjust fetch if needed --
abort if doesn't match tags. Later will adjust acls as needed (if user
sync and not system).

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>