Merge pull request #4758 from xinxinsh/wip-kv-dump-transaction

dump keyvaluestore transaction to a file

Reviewed-by: Haomai Wang <haomaiwang@gmail.com>
Reviewed-by: Varada Kari <varada.kari@sandisk.com>

diff --cc src/common/config_opts.h
Simple merge

diff --cc src/os/KeyValueStore.cc
Simple merge

diff --cc src/os/KeyValueStore.h
Simple merge