[Ozone Upgrade] Add the ability to read block information from Namenode.

When upgrading an HDFS cluster, the user can choose to upgrade with zero data moves. However, it is also a good point to evaluate what-if? conditions and make optimal decisions for both HDFS and Ozone. First step in this process is to learn information about HDFS, FSImage provides then Namespace information, this JIRA will provide the blocks and data nodes part of HDFS.