feat: add Trails sample with polyline rendering

[dkhawk]

This commit introduces a new "Trails" sample to the AdvancedMaps3DSamples app.

Key features and changes:

• Trails Data Model: Defines data classes (Trail, TrailType, DifficultyLevel, DogRegulation, TrailStatus) to represent trail information.
• GeoJSON Parsing: Implements TrailsRepository to read and parse GeoJSON data containing trail information. Includes logic for:
  • Reading from an asset file.
  • Parsing GeoJSON features, properties (including specific OSMP attributes), and LineString geometries.
  • Simplifying trail coordinates using simplify() from com.google.maps.android.ktx.utils.
  • Calculating the LatLngBounds of all trails.
• Polyline Rendering:
  • Adds Mappers.kt with a toPolylineOptions() extension function to convert Trail objects into PolylineOptions.
  • Colors polylines based on trail difficulty (Easy: Green, Moderate: Blue, Difficult: Red).
  • Sets altitudeMode to CLAMP_TO_GROUND and drawsOccludedSegments to true.
• Trails UI:
  • Creates TrailsActivity, TrailsViewModel, and associated composables (MapScreen, LoadingScreen).
  • The TrailsViewModel loads trail data, creates Map3DOptions centered on the trails' boundary, and adds polylines to the map.
  • Displays a loading indicator while data is being fetched.
  • Integrates the ThreeDMap composable for displaying the map.
• Common Map Composable: Refactors ThreeDMap.kt from the scenarios package to the common package to be reused.
• ViewModel Enhancements:
  • Modifies Map3dViewModel to use MutableSharedFlow with replay for currentCamera to ensure observers get the latest value upon subscription.
  • Makes activeMapObjects in Map3dViewModel internal for access within the module.
• MainActivity Update: Adds the "OSMP Trails -- polyline demo" sample to the main list.
• Manifest and Resources: Updates AndroidManifest.xml to include TrailsActivity and adds a new string resource for the sample title.