Special exams MFE feature enabling/disabling

Description

New waffle flag was introduced to enable/disable special exams functionality per course in the MFE app learning. This flag has no effect on the settings ENABLE_SPECIAL_EXAMS feature flag, though it depends on that settings flag value.
This waffle flag is specific per course id.

Setup instructions

Create a new flag in the Waffle flag course overrides in LMS admin.
Set Waffle flag value to courseware.mfe_special_exams
Paste your course id value for which exams should be enabled.
Enable the flag and save