Script for creating new Pod.Cast annotation "rounds"

[akashmjn]

Simplify the process of creating new annotation "rounds".

@scottveirs maintains Orcasound hydrophone events in the Gsheet over time here -- and there's a column for prioritizing which events are optimal for annotation rounds in Pod.Cast | Help listen for Orcas!.

Creating a new round involves the following:

• Pulling audio files from Orcasound AWS S3 and breaking them into 1 min *.wav chunks
• Processing these *.wav chunks with a model and save predictions in corresponding JSON files
• (optional) filter out very low confidence chunks to reduce annotation burden
• Uploading these files in appropriate structure to Azure Blob
• No update is required to the flask web-app, things will be available under the /roundN suffix to the URL

Identifying interesting events from the GSheet is OK to trigger manually now - this issue is for a prepare_for_podcast.py script to simplify the rest of it.

[akashmjn]

@scottveirs - I think we have this script on the aifororcas-livesystem repo, that needs to be cleaned up & added to this repo.