Bulk Create Interface Submission Feature

[TristanThrush]

Plan:

• A button in the upper right of the create interface that opens a modal.
• The modal will contain a place for an examples jsonl file upload.
• If the task has contexts, then the uploader must supply a context id (cid) as a field in the examples jsonl file, for every example.
• Behind the scenes, the current plan is for the frontend to read the examples from the jsonl file one-by-one, using the normal create interface api calls to get model predictions and save the examples in the db. Let me know @douwekiela if you think it makes more sense for me to code a custom batch transform job function instead, though. That would likely be better if the example submissions are expected to be large.

Note: with this feature, it is also necessary to implement a feature allowing the task owner to download context ids for every context that they have uploaded, so that they can let participants know which cid goes to which context