Showing a locality POI should use an "outline" rather than a "pin" UI #163

From #161 (comment)

Currently, after searching for a POI we render a pin at the POI's position. This works well enough for small things like a shop, but when the POI is a big entity like an entire city, it seems inappropriate and arbitrary to render a pin.

Instead of a pin, we should render an outline or a polygon to highlight the entire area of the locality.