GitLab Migration - export relations compressed with zip

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Work on this issue
• Close this issue

As discussed in POC #376261 (closed) GitLab Migration should start exporting relations compressed with zip.

Proposed solution

1. Update API::GroupExport & API::ProjectExport to accept new optional query param use_zip = true
2. Update BulkImports::RelationExportService to utilize this flag and export relations compressed in zip if use_zip = true
3. If flag is missing or false, use old exporting logic of exporting in tar.gz format
4. Decompressed contents should remain identical to ones from tar.gz to be able to process data on Import side without any changes to directory/file structure