Download Projects as a Zip

This is a proof of concept, showing how to download Val Town projects as zip files. For now, I've hardcoded my username into the code, so you can only download my public projects as zip files. To see it working, type the name of this project getProjectsAsZips and press download. Waalaah!

If you fork this project, you can update the hardcoded username in frontend/MessageInput.tsx. I used forked this project template to get started quickly (it's great), hence the weird naming and leftover code you'll see around this project.

I'd love it if someone wanted to send me a PR and tackle either of these two:

1. Add ability for users to input their own username
2. Add ability for users to input their API token so they can see private projects