Currently, the /login_ajax endpoint does not regard any `next` or `course_id` parameters. This commit changes that, sharing the logic that /login (which the current templated login page uses) employs to cacluate a redirect-after-login URL based on `next` and `course_id`. The new functionality is behind ENABLE_LOGIN_MICROFRONTEND.
common ------ This directory contains common code shared between LMS and CMS, such as Mako templates, CSS, and Coffescript.