Make Overpass query script more generic

[joergreichert]

At the moment the overpass query is only available for parks
https://github.com/CodeforLeipzig/leipzigmaps/blob/main/src/transformers/leipzig-parks.js

Make it general available to scrape new data for a given overpass query like

• public/data-query/leipzig-busstops.overpassql
• public/data-query/leipzig-daycares.overpassql
• public/data-query/leipzig-fitness-studios.overpassql
• and more (see other openstreetmap labled tickets)