Summary:
Previously the Java implementation of `RocksDB#addFile` was both incomplete and not inline with the C++ API.
Rather than fix it, as I see that `rocksdb::DB::AddFile` is now deprecated in favour of `rocksdb::DB::IngestExternalFile`, I have removed the old broken implementation and implemented `RocksDB#ingestExternalFile`.
Closes https://github.com/facebook/rocksdb/issues/2261
Closes https://github.com/facebook/rocksdb/pull/2291
Differential Revision: D5061264
Pulled By: sagar0
fbshipit-source-id: 85df0899fa1b1fc3535175cac4f52353511d4104
