check_ version for test_object_accessed

[filipsch]

test_object_accessed is the last function that doesn't have a check_ counterpart.

The alternative is to get rid of it. The function is used in 40 exercises, it is no longer documented, and SCT authors don't seem to need it:

   course_id count link                                 
       <int> <int> <chr>                                
 1      1115     7 https://www.datacamp.com/courses/1115
 2      1532     1 https://www.datacamp.com/courses/1532
 3      1639     1 https://www.datacamp.com/courses/1639
 4      1650     1 https://www.datacamp.com/courses/1650
 5      1681     5 https://www.datacamp.com/courses/1681
 6      1939     3 https://www.datacamp.com/courses/1939
 7      2023     6 https://www.datacamp.com/courses/2023
 8      2072     6 https://www.datacamp.com/courses/2072
 9      5226     9 https://www.datacamp.com/courses/5226
10      6030     1 https://www.datacamp.com/courses/6030