[Feature Request]: Lesson download script improvements for multiple classrooms

[BenHenning]

Is your feature request related to a problem? Please describe.

There are a number of changes to the lesson download script needed in order to better prepare for the upcoming GA launch.

Describe the solution you'd like

The script needs to be updated to:

• Add stats for per-topic sizes (compressed/uncompressed including images).
• Pull both math and science classrooms (verify classrooms on the backup migration server to verify that we can pull non-published classrooms).
• Ensure all output is properly as specific as possible (to corresponding structures) and can be outputted as a CSV file for processing.
• Update the CI workflow to upload the CSV file as an artifact for sheets processing.
• Maybe: Use the 'all classrooms' controller rather than hardcoding math/science (need to verify this against published/unpublished).

Describe alternatives you've considered

No response

Additional context

No response

[BenHenning]

/cc @seanlip as this was in response to our GA planning discussion today.