Don't allow confusion pairs with same term and confused-term #3
Description
From quizfreely/quizfreely#57:
For term confusion pairs, Quizfreely's backend API and IDB API layer should not allow pairs where the term and confusedTerm are the same. If confusion pairs cannot have the same term and confused-term, then the correct answer can't appear as a duplicate answer choice from confusion pairs.
The API shouldn't allow confusion pairs with the same term and confusedTerm, cause that wouldn't be an incorrect answer.
Right now, I'm pretty sure it allows whatever combination of term ids the client gives it. Making it reject wrong confusion pairs will make debugging client-side code easier in the future.