Cover linear progress within lessons with tests

Problem/Motivation

Automated tests must cover as much as possible features in Anu LMS to avoid bugs during development of new features.

Acceptance criteria

• Test covers ability to progress only lesson-by-lesson when course linear progress feature is enabled
• Access checks should be done as part of tests to make sure that students who didn't complete previous lessons can't access locked lessons by direct URLs

Tech concept

• Rename CoursesCreationTest and CoursesPageCreationTest to CourseTest.php and CoursesPageTest.php.
• Extend "CourseTest" file.
• Create a new course with 3 lessons (content no matters), set "Enable linear progress" for that course.
• Try directly open the 2nd lesson using an absolutely URL, a user should be redirected to the main page. Try the same with 3rd lesson.
• After that open 1st lesson and pass through all steps (Next button). That should work well.
• After that make sure that 2nd and 3rd lessons can be opened using absolutely URLs.
• Un-tick "Enable linear progress" for that course and hit Save.
• Create a new user and make sure any lesson from that Course can be opened directly.