pb-2178: Obtain object-lock info for S3 bucket
pb-2178: Obtain object-lock info for S3 bucket

Added a function to objectstore package to extract object lock info from
a S3 bucket.

Signed-off-by: Lalatendu Das <298fa1936b82486d6ca337c54cac35f903c3b12d@purestorage.com>

libopenstorage/stork,libopenstorage/stork,libopenstorage/stork