chore: Convert data types to Kotlin

[dkhawk]

This pull request refactors several core data classes from Java to Kotlin. This modernization improves code readability, safety, and conciseness by leveraging Kotlin features like properties, val, and non-nullable types.

Summary of Changes

• DataPolygon.java -> DataPolygon.kt: Converted the DataPolygon interface to Kotlin. It now uses val properties for outerBoundaryCoordinates and innerBoundaryCoordinates.
• Feature.java -> Feature.kt: Converted the Feature class to Kotlin. This includes:
  • Replacing Java getters and setters (getGeometry, getProperties, hasProperty) with Kotlin properties (geometry, properties, hasProperty).
  • Using a private backing property (_properties) for the mutable map to expose an immutable view.
• Geometry.java -> Geometry.kt: Converted the Geometry interface to Kotlin, using val properties for geometryType and geometryObject.
• Layer.java -> Layer.kt: Converted the Layer abstract class to Kotlin. It now uses generic types for Feature and uses Kotlin's property access syntax for renderer (renderer.map instead of renderer.getMap()).
• LineString.java -> LineString.kt: Converted the LineString class to Kotlin, using val properties for its data and adding equals and hashCode implementations.
• MultiGeometry.java -> MultiGeometry.kt: Converted the MultiGeometry class to Kotlin. The constructor now enforces non-nullability, and the getGeometryType method is replaced with an override property.
• Point.java -> Point.kt: Converted the Point class to Kotlin, using val properties for its data and including equals, hashCode, and toString overrides.