Sync meta.json file during Checkpoint

In Checkpoint we are not syncing the meta.json file during Checkpoint after write. It contains the replayOffset for datalog. The issue is not in 7.0 and onwards because we do not use checkpoint file.

        data, _ := json.Marshal(meta)

        if err := ioutil.WriteFile(

                path.Join(tmpDir, "meta.json"), data, 0755); err != nil {

                return err

        }

 https://github.com/couchbase/plasma/blob/mad-hatter/persistor.go#L271