Parse unique locations from events

[BeniRupp]

We use all upcoming and all events within the last 52 weeks to figure out 'active' Hackergarten locations.

The venue of the event is used as sponsor. Later on we can add all different venues of a location to the sponsors list.

We parse the link of the meetup group from the event link with no fallback.

TODOs:

• [ ] The citiy in the title should be replaced by the city of the address.
• [ ] Long and Lat should be determined using the address and the openstreetmap api (used in hero-geo-location npm package).
• [ ] Use modern JS to simplify the code.
• [ ] Use the generated locations.json file in scripts/locations.js