Utilize OOB upgrade message processing for writes

After HDFS-5585 and HDFS-5583, clients and datanodes can coordinate shutdown-restart in order to minimize failures or locality loss.

In this jira, HDFS client is made aware of the restart OOB ack and perform special write pipeline recovery. Datanode is also modified to load marked RBW replicas as RBW instead of RWR as long as the restart did not take long.

For clients, it considers doing this kind of recovery only when there is only one node left in the pipeline or the restarting node is a local datanode. For both clients and datanodes, the timeout or expiration is configurable, meaning this feature can be turned off by setting timeout variables to 0.