rgw/restore: Add notifications for restore events

rgw/restore: Add notifications for restore events

The following notification events are added for restore operations as stated
in https://docs.aws.amazon.com/AmazonS3/latest/userguide/notification-how-to-event-types-and-destinations.html

s3:ObjectRestore:*
s3:ObjectRestore:Post
s3:ObjectRestore:Completed
s3:ObjectRestore:Delete

By using the ObjectRestore event types, you can receive notifications for event initiation and
completion when restoring objects from the S3 Glacier Flexible Retrieval storage class,
S3 Glacier Deep Archive storage class, S3 Intelligent-Tiering Archive Access tier, and
S3 Intelligent-Tiering Deep Archive Access tier. You can also receive notifications for when the restored copy of an object expires.

The s3:ObjectRestore:Post event type notifies you of object restoration initiation. The s3:ObjectRestore:Completed
event type notifies you of restoration completion. The s3:ObjectRestore:Delete event type notifies you when
the temporary copy of a restored object expires.

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