Provide more information about each POI

[1ec5]

In the iOS implementation in mapbox/mapbox-gl-native#9950, each accessible place is labeled with its name but also given an “accessibility value” that provides the following facts:

• The kind of place, using a cleaned-up type property that’s more or less extracted from OpenStreetMap tags
• The kind of airport, rail station, or mountain based on its Maki image name
• The peak’s elevation in the units preferred by the user’s locale

https://github.com/mapbox/mapbox-gl-native/blob/dcd7da14f6627a09a5840a3046b5708449962f69/platform/ios/src/MGLMapAccessibilityElement.mm#L87-L119

/cc @tristen