Always add `sys` columns to all tables

[dreadatour]

For now in few cases datasets tables have no sys columns (sys__id and sys__rand), for example, aggregation result dataset by default comes without these tables.

We need to:

1. Check all the codebase and always add sys columns.
2. Check all the codebase where we are expecting datasets to do not have sys columns and remove all hacks we have for this case.
3. Tests.