Make sure usage entries are sorted after collecting parent usages of constructors, fields and class members

- Adapt to performance enhancements in Database.Native returning [!!]
  from getEntries
- Add type_synonyms index array to avoid walking through entire database
  on unification queries

Early fail for bad matches of small queries (e.g. one-letter queries from the VSCode plugin) to speed up ranking

Use unambiguous [TVAssignment] instead of Unifier to figure out required context to avoid variable clashes (e.g. 'select :: [a] Int -> a' would require Array [] [] instead of Array [] a)