feat: Adds statement for multichoiceset quiz answers. (#235)

classes/log/store.php

lang/en/logstore_xapi.php

settings.php

...sformer/events/mod_quiz/question_answered/multichoice.php

src/transformer/utils/get_multichoice_definition.php

tests/mod_quiz/attempt_submitted/multichoice/data.json

tests/mod_quiz/attempt_submitted/multichoice/statements.json

..._quiz/attempt_submitted/multichoice_withchoices/data.json

...quiz/attempt_submitted/multichoice_withchoices/event.json

...attempt_submitted/multichoice_withchoices/statements.json

...d_quiz/attempt_submitted/multichoice_withchoices/test.php

tests/mod_quiz/attempt_submitted/multichoiceset/data.json

...mod_quiz/attempt_submitted/multichoiceset/statements.json

...iz/attempt_submitted/multichoiceset_withchoices/data.json

...z/attempt_submitted/multichoiceset_withchoices/event.json

...empt_submitted/multichoiceset_withchoices/statements.json

...uiz/attempt_submitted/multichoiceset_withchoices/test.php

tests/xapi_test_case.php