feat(kmp-demo): add shared multiplatform Location Flow demo

[dkhawk]

Summary

Adds a shared Location Flow demo (LocationFlowDemo) to :maps-compose-multiplatform-demo exercising the multiplatform Location, LocationSource, and LocationPriority APIs from googlemaps/android-maps-utils#1817 across Android and iOS:

• Dependency Wiring (gradle/libs.versions.toml, maps-compose-multiplatform/build.gradle.kts, settings.gradle.kts):
  • Adds maps-utils-kmp-core (com.google.maps.android:android-maps-utils-core) and exposes it via api(libs.maps.utils.kmp.core) in :maps-compose-multiplatform commonMain.
  • Scopes mavenLocal() in settings.gradle.kts (when useMavenLocal=true) to includeGroup("com.google.maps.android") so local KMP snapshot testing does not conflict with external dependencies.
• Platform Location & Permission Controller (PlatformLocationSource.kt, PlatformLocationSource.android.kt, PlatformLocationSource.ios.kt):
  • Implements rememberPlatformLocationController() backed by LocationManager on Android and CLLocationManager.asLocationSource() on iOS, tracking runtime location permission state and providing permission request / system settings actions.
• Shared LocationFlowDemo (DemoApp.kt, Demos.kt):
  • Collects LocationSource.locationEvents() in commonMain to animate the camera, update a live Marker, render a horizontal accuracy Circle, and draw a breadcrumb Polyline trail, with interactive High Accuracy / Balanced priority switching and runtime permission recovery controls.
• App Manifests & Xcode Project Generation (maps-app/src/main/AndroidManifest.xml, iosApp/iosApp/Info.plist, iosApp/create_project.rb):
  • Declares ACCESS_COARSE_LOCATION and ACCESS_FINE_LOCATION in maps-app and NSLocationWhenInUseUsageDescription in iosApp.
  • Updates iosApp/create_project.rb to check IOS_MAPS_API_KEY in secrets.properties before falling back to MAPS_API_KEY.

Note: Depends on googlemaps/android-maps-utils#1817 being merged and published to 6.1.0-SNAPSHOT for CI resolution.

Testing

• Verified live on physical Android device (Pixel 6) and physical iOS device (iPhone 14) as well as iOS Simulator.