Change the `insert_building()` and `get_all_buildings_in_tile()` functions to use the new building attribute `height`.

The functions insert_building(), import_from_postgis() and get_all_buildings_in_tile() need to be changed to use the new field height instead of the field storeys. Additionally, a test should be implemented to check the modified functions.

\rfc @laurens @gislars @kasra @tara