The main goal is to improve consistency and reduce the number of poi without an icon.
- Remove music from poi cultural, music has only two subclasses music and musical_instrument, both are styled as poi shop
- Remove arts_centre from poi shop, it's already styled as poi cultural
- Remove chocolate icon, chocolate uses confectionery icon (see: https://github.com/openmaptiles/openmaptiles/pull/1628)
- Remove references to ice_cream class from poi shop
- Add missing gallery icon and move it to poi cultural (see: https://wiki.openstreetmap.org/wiki/Tag:tourism%3Dgallery)
- Use the icons alcohol, newsagent, perfumery, trade respectively for wine, kiosk, perfume and wholesale.
- Add a generic fallback icon for shops
