Implement a function to retrieve all tiles within a boundary at the desired zoom level
In case of large countries, some queries in the Initalizer are failing due to the large size of the queried area and the complex processing in the tile_best_estimate
view. To mitigate this situation, we can divide the country into large tiles of low zoom level and process these tiles separately, hereby reducing the load caused by the queries. This function will need to be implemented in two versions, one for PostGIS and one for SpatiaLite.