Export multiple courses

[taylortom]

⚠️ CODE TO FOLLOW ⚠️

I've built a prototype to allow export of multiple courses (with the purpose of using as a rudimentary back-up system).

Is this something that would be useful in the open-source product?

Related to to #1091

Features:

• Separate UI (not part of the single-page app)
• Lists all courses with checkboxes
• Can auto-select:
  • All
  • None
  • Not exported
  • Updated since last export
• Courses built in series, and added to a single zip
  • Have to be built in series due to the current restrictive build process which cleans out temp files prior to each build

[Link2Twenty]

Currently, we export our courses after we make a few changes and push the files to an internal git, this helps us keep track of changes and allows us to have rollback points.

I can see a mass export being helpful for people that don't do this.

[moloko]

@Link2Twenty seems like it would also be useful to be able to connect the AAT to a version control system so that a process like this could be fully integrated. We do something similar here at Kineo, only with Subversion rather than Git.

EDIT: see #1819

[memeteli]

Would be a fan of this feature.