[FEATURE] Min polygon area for including center point

[msbarry]

"include a point at the the center of this polygon when the polygon's tile area is at least X pixels" seems like a common use-case that should be pushed down into planetiler. Maybe reuse .setMinPixelSize(...) which currently doesn't have any meaning for points or a new feature method: .whenFeatureSizeExceeds(...)

Originally posted by @msbarry in openmaptiles/planetiler-openmaptiles#126 (comment)