Summary:
The write unix time from non L0 files are not surfaced properly because the level's wrapper iterator doesn't have a `write_unix_time` implementation that delegates to the corresponding file. The unit test didn't catch this because it incorrectly destroy the old db and reopen to check write time, instead of just reopen and check. This fix also include a change to support ldb's scan command to get write time for easier debugging.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/13057
Test Plan: Updated unit tests
Reviewed By: pdillinger
Differential Revision: D64015107
Pulled By: jowlyzhang
fbshipit-source-id: 244474f78a034f80c9235eea2aa8a0f4e54dff59
2fef013616