Allow video files to be run through other models

[anishapai]

We can modify the /predict endpoint so that when a video comes in, it is converted to audio and text as well, as per the user's request (this would involve thinking about the front-end UI first, and what is the most intuitive way to present options to the investigator before tackling the back-end). This issue deals with the front-end.

In the back-end, this would be done by adding a clause to the prediction pipeline that is something like:

if file type is video and audio models are selected:
  1. convert files to audio 
  2. run predictions on audio models.

Things to think about:

• For step 2, the same create_new_prediction function can be called.
• Would recommend abstracting this clause to a helper function because the create_new_prediction function for readability
• There is a model_type parameter in the create_new_prediction function. Is this still necessary?
• The user could select both video and audio models, so video prediction should still be run in that case.