[snapshot] Ozone snapshot diff should provide an option for displaying output as json format

# ozone sh snapshot diff --help
Usage: ozone sh snapshot diff [-chV] [-p=<pageSize>] [-t=<token>] <value>
                              <fromSnapshot> <toSnapshot>
Get the differences between two snapshots
      <value>           URI of the volume/bucket.
                        Ozone URI could either be a full URI or short URI.
                        Full URI should start with o3://, in case of non-HA
                        clusters it should be followed by the host name and
                        optionally the port number. In case of HA clusters
                        the service id should be used. Service id provides a
                        logical name for multiple hosts and it is defined
                        in the property ozone.om.service.ids.
                        Example of a full URI with host name and port number
                        for a key:
                        o3://omhostname:9862/vol1/bucket1/key1
                        With a service id for a volume:
                        o3://omserviceid/vol1/
                        Short URI should start from the volume.
                        Example of a short URI for a bucket:
                        vol1/bucket1
                        Any unspecified information will be identified from
                        the config files.      <fromSnapshot>    from snapshot name
      <toSnapshot>      to snapshot name
  -c, --cancel          Request to cancel a running SnapshotDiff job. If the
                          job is not IN_PROGRESS, the request will fail.
  -h, --help            Show this help message and exit.
  -p, --page-size=<pageSize>
                        number of diff entries to be returned in the response
                          (optional)
  -t, --token=<token>   continuation token for next page (optional)
  -V, --version         Print version information and exit.