Switch map server to Geoapify and integrate mapbox gl to render their vector tiles

What does this MR do?

We will use Geoapify as the new map server. Since, leaflet can not render vector tiles I needed to additionally integrate the mapbox gl library.

To make it work locally, I needed to make some changes with the content security policy.

How confident are you it won't break things if deployed?

I had some issues with setting up the content security policy. Would be good if someone can take a look at it with more experience with this stuff :)

Links to related issues

Related Slack Thread: https://yunity.slack.com/archives/CRL49VCJ1/p1581190646053100

How to test

Steps a reviewer can take to verify that this MR does what it says it does e.g.

1. Checkout branch locally
2. Login as foodsaver
3. Test whether the map is displayed properly at the following places
   • The global map under /karte http://localhost:18080/karte
   • The address pick map under settings http://localhost:18080/?page=settings&sub=general
   • The map on a basket detail page http://localhost:18080/essenskoerbe/38971
   • The find basket map (click on the basket in the topbar and then on "all baskets") http://localhost:18080/essenskoerbe/find
   • The region admin tool http://localhost:18080/?page=region (log in as orga)

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))
• Once your MR has been merged, you are responsible to update the #foodsharing-beta Slack channel about what has been changed here. They will test your work in different browsers, roles or other settings