Cover courses pages with tests [#3308596]

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

Test covers creation of courses page with one or several course categories selected
Test covers linear progress of courses
Test covers sorting of courses within a category

Add course category "Animals" and "People"
Create 3 Courses (Birds, Fishes and Snakes) with Animals category
Create 2 Courses (British, England) with People category
Create Courses page with 1 Category "People"
Hit Save and make sure that it sidplays properly
Hit Edit and add 2nd Category "Animals" to there, save it and make sure 2nd Category is appeared there
Edit again and change order for Categories (order: Animals, People), hit Save and make sure that changes were applied.
Set linear progress for "Animals" category and make sure it affects Courses page.

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3308596-cover-courses-pages changes, plain diff MR !17
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