Add boolean parameter 'showAllAssignedCourses' in function 'getCoursesFo...

...llowedByUser' to retrieve all assigned courses if needed - refs #7296
Please, see function's declaration second argument:
public static function getCoursesFollowedByUser(
        $user_id,
        $status = null,
        $from = null,
        $limit = null,
        $column = null,
        $direction = null,
        $getCount = false,
        $keyword = null,
        $sessionId = null,
        $showAllAssignedCourses = false
    )