Issue #3479063: Add data integrity checks

lms.module

lms.services.yml

src/DataIntegrityChecker.php

src/Entity/Activity.php

src/Entity/ActivityType.php

src/Entity/Answer.php

src/Entity/Bundle/Course.php

src/Entity/Form/ActivityDeleteForm.php

src/Entity/Form/ActivityForm.php

src/Entity/Form/ActivityTypeDeleteForm.php

src/Entity/Form/ActivityTypeForm.php

src/Entity/Form/AnswerEvaluationForm.php

src/Entity/Form/AnswerForm.php

src/Entity/Form/LessonDeleteForm.php

src/Entity/Form/LessonForm.php

src/Entity/Lesson.php

src/Entity/LessonStatus.php

src/Form/AnswerFormTrait.php

src/Form/DataIntegrityWarningTrait.php

src/Form/Modal/ModalEntitySubformTrait.php