Relational Connections: Inherit from Base Schema Rather Than Duplicating

[spicy-sauce]

From Oren:

I merged it, although the more elegant solution would be to have the schema inherit from some base schema since we just duplicate those query and connect_args for each single connector.

It would be great to refactor the code to use inheritance from a base schema instead of duplicating query and connect_args for each individual connector. This would result in a more elegant and maintainable solution.