add wikimedia commons as an photo service

[k-yle]

Closes #10640

images from Wikimedia Commons are now available alongside streetlevel imagery like Mapillary:

This uses Mediawiki's Geosearch+Imageinfo API (example), which was discussed in https://github.com/openstreetmap/iD/issues/10640#issuecomment-3137220974

The PR is a draft because it's blocked by several other PRs, and there are a lot of issues to consider:

• [ ] the API only provides basic metadata and EXIF data, but not structured data.
  • [ ] therefore, the date is the uploaded date, not the capture date. which could be years apart.
  • [ ] therefore, the username is the uploader, not the author. which is often different (e.g. flickr2commons)
  • [ ] no support for heading/bearing yet, although this could be obtained from the EXIF (GPSImgDirection & co.) if we decide not to use structured data.
• [ ] there's no filter to exclude incompatible licenses yet. I'm guessing CC-0 is the only compatible license?
  • [ ] The license information comes from LicenseShortName. There is a also a boolean called AttributionRequired, maybe we could filter based on AttributionRequired=false instead of hardcoding compatible license names ?