Context

Our current kartotherian tm2 source is based in some complicated SQL queries in order fetch GIS data from the DB.
As part of the improvements we are planning to simplify this by using an SQL function per layer so all the logic and helpers are maintained in the PostgreSQL level.

Here is some work in progress: https://github.com/wikimedia/maps-config

Acceptance criteria:

• Migrate tm2 source queries to use the new query structure