[Ndjson][Preparation Work] Introduce export.rake job for exporting project

Based on conversation related to preparation work needed for Introducing .ndjson as a way to process import, mentioned in the comment: #197171 (comment 289977581)

As part of preparation work we should ship export.rake task similar to import.rake, so we could easily measure export, with and without ndjson changes.

Related to #197171 (closed)