Investigate moving TSTabletManager::VerifyTabletData() into a shared class

[jmeehan16]

It's likely that we will want to move VerifyTabletData() into a shared class so that it can be used to verify the master tablet data as well. However, to do so will require a bit of investigation to make sure we can do that safely. The code block in question:

void TSTabletManager::VerifyTabletData() {
  LOG_WITH_PREFIX(INFO) << "Beginning tablet data verification checks";
  for (const TabletPeerPtr& peer : GetTabletPeers()) {
    if (peer->state() == RUNNING) {
      if (PREDICT_FALSE(FLAGS_skip_tablet_data_verification)) {
        LOG_WITH_PREFIX(INFO)
            << Format("Skipped tablet data verification check on $0", peer->tablet_id());
      } else {
        Status s = peer->tablet()->VerifyDataIntegrity();
        if (!s.ok()) {
          LOG(WARNING) << "Tablet data integrity verification failed on " << peer->tablet_id()
                       << ": " << s;
        }
      }
    }
  }
}

If moveable, one possible location may be the TabletMemoryManager. @bmatican