Properties generated for PK in 4.1 has issues (see
CAY-2565), so we need some logic to deal with them.
Instead of using DbPath directly we can make special type of Property (probably IdProperty) to make them usable in all cases.
Required cases to handle:
- compatibility with dot() operator
- in-memory sorting
- in-memory evaluation
My approach is to use special name "@id" as path for PK. Limitation - it will be unusable with compound PKs.