Follow-up from "Export rake task"

The following discussions from !25598 (merged) should be addressed:

• @splattael started a discussion: (+3 comments)

  Not blocking: Probably out of scope and maybe somewhat personal preferences but I wonder moving this class to, say lib/gitlab/import_export/export_task.rb would improve/speed-up specs as there's no need to invoke rake tasks?

• @splattael started a discussion:

  Not blocking: If we'd move this into lib/gitlab/import_export/export_task.rb we could inject output here and do output.puts 'Done!'.

• @splattael started a discussion:

  Not blocking: Similar to the comment above.

  How about moving this class to lib/gitlab/import_export/import_task.rb?