feat: Adds statement for essay quiz questions. (#194)

.editorconfig

...r/events/mod_quiz/attempt_submitted/attempt_submitted.php

...transformer/events/mod_quiz/attempt_submitted/handler.php

src/transformer/events/mod_quiz/question_answered/essay.php

...transformer/events/mod_quiz/question_answered/handler.php

src/transformer/get_event_function_map.php

tests/mod_quiz/attempt_submitted/essay/data.json

tests/mod_quiz/attempt_submitted/essay/event.json

tests/mod_quiz/attempt_submitted/essay/statements.json

tests/mod_quiz/attempt_submitted/essay/test.php

tests/mod_quiz/attempt_submitted/no_questions/data.json

tests/mod_quiz/attempt_submitted/no_questions/event.json

...s/mod_quiz/attempt_submitted/no_questions/statements.json

tests/mod_quiz/attempt_submitted/no_questions/test.php

tests/mod_quiz/attempt_submitted/unknown_qtype/data.json

tests/mod_quiz/attempt_submitted/unknown_qtype/event.json

.../mod_quiz/attempt_submitted/unknown_qtype/statements.json

tests/mod_quiz/attempt_submitted/unknown_qtype/test.php