rgw/CloudTransition: Update object metadata and bi post cloud tranistion

rgw/CloudTransition: Update object metadata and bi post cloud tranistion

After transitioning the object to cloud, following updates are done
to the existing object.

* In bi entry, change object category to CloudTiered
* Update cloud-tier details (like endpoint, keys etc) in Object Manifest
* Mark the tail objects expired to be deleted by gc

TODO:
* Update all the cloud config details including multiparts
* Check if any other object metadata needs to be changed
* Optimize to avoid using read_op again to read attrs.
* Check for mtime to resolve conflicts when multiple zones try to transition obj

Signed-off-by: Soumya Koduri <skoduri@redhat.com>