Summary:
SstFileManager move files that need to be deleted into a trash directory.
Deprecate this behaviour and instead add ".trash" extension to files that need to be deleted
Closes https://github.com/facebook/rocksdb/pull/2970

Differential Revision: D5976805

Pulled By: IslamAbdelRahman

fbshipit-source-id: 27374ece4315610b2792c30ffcd50232d4c9a343