Test different problem types.

common/test/data/blocks/capa.xml

common/test/data/blocks/coderesponse.xml

common/test/data/blocks/library_content.xml

common/test/data/blocks/lti.xml

common/test/data/blocks/openassessment.xml

lms/djangoapps/grades/tests/test_grades.py

lms/djangoapps/grades/tests/test_new.py

openedx/core/lib/xblock_utils/__init__.py

openedx/core/lib/xblock_utils/test_utils.py