[main] Addressed race condition issue with TranslatorState.NonVisitableExpressions
[main] Improved working with nullable enum constants in queries
[main] Improved compatibility of .ToListAsync/.ToArrayAsync/.ToHashSetAsync/.AsAsyncEnumerable extension methods with EntitySet
[postgresql] Improved database structucture extraction
[postgresql] Addressed certain cases of decimal results of aggregate operations being unable to fit to .NET decimal