Migrate scrapeSingleHearing Firebase Function to V2

[Mephistic]

Summary

In order to stay up-to-date with our Firebase versions, we need to begin migrating our existing V1 Firebase Functions to V2 Firebase functions.

A good place to start is with the new scrapeSingleHearing firebase function - its behavior isn't user-facing and we can cope with a bit of downtime, so it should make a safe testcase for the migration process.

Success Criteria

• scrapeSingleHearing function has been migrated to a V2 Firebase Function

Additional Links

• V2 Migration Guide: https://firebase.google.com/docs/functions/2nd-gen-upgrade