Placemark localization for (OSM) vector rendering

Summary:
In OpenStreetMaps, the placemarks are now shown in the local language of the viewer, provided that proper mapping of that language is available. If no mapping is found, the local name of the placemark is shown.

Working:
1. Determines the language code of the placemark.
2. Determines the language of the viewer in order of preference.
3. Chooses the best translation alternative and displays that.

{F45339}

Reviewers: #marble, nienhueser

Subscribers: #marble, nienhueser

Projects: #marble

Differential Revision: https://phabricator.kde.org/D844