rgw: add a field to store generic user data in the bucket index,

rgw: add a field to store generic user data in the bucket index,
that can be populated/fetched via a configurable custom http header

Signed-off-by: Pavan Rallabhandi <prallabhandi@walmartlabs.com>
(cherry picked from commit abca7a86c3cfbb58fafb5d057d9d6f5017a53704)

Conflicts:
	src/rgw/rgw_op.cc
		Number of arguments to RGWPutObjProcessor_Multipart::do_complete has been changed in master with an extra field accounted_size added, which is not required in Jewel.
        	Number of arguments for the processor->complete() has been changed in master, which is not required in Jewel.

	src/rgw/rgw_op.h
		A new member field `crypt_http_responses` is added in the class `RGWPutObj` in master, which is not required in Jewel.

	src/rgw/rgw_rados.cc
        	In the function RGWPutObjProcessor::complete() there is an extra argument to do_complete() in master, which is not required in Jewel.
        	In the function RGWPutObjProcessor_Atomic::do_complete, a call to obj_op.write_meta has accounted_size, which is not required in Jewel.
        	There is an extra argument accounted_size in RGWRados::Bucket::UpdateIndex::complete in master, which is not required in Jewel.
        	In RGWRados::Bucket::UpdateIndex::complete, RGWObjEnt has been removed in master, which has to be retained in Jewel.
        	In RGWRados::cls_obj_complete_op, user_data is added to the rgw_bucket_dir_entry_meta structure.
        	In RGWRados::cls_bucket_list, the user_data field of RGWObjEnt is populated.

	src/rgw/rgw_rados.h
        	In UpdateIndex::complete(), remove_objs is of type rgw_obj_key in Jewel instead of rgw_obj_index_key
        	Corrected various function declarations as appropriate.
        	RGWPutObjProcessor_Multipart is not part of this file in Jewel.

	src/rgw/rgw_rest_swift.cc
		In RGWListBucket_ObjStore_SWIFT::send_response(), accounted_size is not required in Jewel.

	src/rgw/rgw_common.h
		Add user_data field in RGWObjEnt structure.

	src/rgw/rgw_json_enc.cc
		Add user_data field while dumping RGWObjEnt.