Add new columns to Summer workshop gsheet

[molly-moen]

PLC-902
Add new columns virtual and third_party_provider to the summer workshop gsheet export. The virtual column will either contain TRUE or be empty for a non-virtual workshop. As of now the only third party provider is Friday Institute, so that column will either contain friday_institute or be blank.
This will also update our workshop csv export.

Testing story

Tested via the process described here.

Reviewer Checklist:

• Tests provide adequate coverage
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[islemaster]

👍 Probably worth noting that this also modifies our workshop dashboard CSV downloads. I think that's fine.