Course-team-authored JS expects $$course_id to be defined
in the global scope. This has worked fine in Legacy courseware,
but due to some differences in page loading (which I don't
understand) between Legacy and Chromeless (ie New/MFE) XBlock
rendering templates, $$course_id wasn't being assigned before
course-team-authored JS was run, causing the scripts to break
on the undefined variable.
The fix here is to assign $$course_id in the <head>,
guaranteeing that the variable is assigned before
any other JS is run.
TNL-7993
90be80e645