Optimize instantiating of the entities by reusing of the data

[srokap]

Previously discussed here: ​https://docs.google.com/document/d/1NrxIj4YOTjNbeXDGW3tpz2lNvaRwL2NDPBNd7TgRfFk/edit?disco=AAAAAEr6svk

Me: If we select object entities only, we already know that we'll need data from additional table to instantiate it by callback function. It's MUCH faster to make single query

Evan: More generally, if someone specifies a single type, we should just join with the appropriate table to avoid another query for each entity.