Batch JSONL Output

[kchason]

Proposed changes

Similar to the batch logic in #5688, this adds the ability to batch outputs in the JSONL export to avoid retaining the entire result set in memory.

Checklist

• Pull request is created against the dev branch
• All checks passed (lint, unit/integration/regression tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[GeorginaReeder]

Thanks so much for your contribution @kchason ! :)