Dictionary: Use the same headword comparison and transformation functions as dictfmt

[baskerville]

• The transformation that was applied by dictfmt on the original headwords needs to be applied to the query. We're already transforming the query but we need to check that the transformation is exactly the same.
• The non fuzzy strategy is binary search, so the index should stay the same if sorted using Rust's string comparison function. We want to check that assumption.