Import utils from tasks

Refs https://redmine.teklia.com/issues/6067

As we are splitting the tasks into different workers, we need to share some common utils.

Please port the module arkindex_tasks.utils as teklia_toolbox.requests

You can skip the is_json_file as it's unused.

Both constants HTTP_GET_RETRY_BACKOFF & DOWNLOAD_CHUNK_SIZE should also be ported over