Add Android turn-by-turn navigation tutorial app

[esoekianto]

Summary

Adds the source for the android-navigation tutorial — a Kotlin + Jetpack Compose app
using Mapbox Navigation SDK v2's drop-in NavigationView, mirroring the ios-navigation
tutorial's flow: pick a destination from a list → calculate a route → present full-screen,
voice-guided turn-by-turn navigation.

Note: Navigation SDK v3 for Android does not yet ship a drop-in turn-by-turn UI (confirmed
against both Mapbox's v3 migration guide and the actual SDK artifacts), so this tutorial
uses the stable v2 ui-dropin-ndk27 package instead, matching the level of integration
effort the iOS tutorial has with NavigationViewController.

Test plan

• ./gradlew :app:assembleDebug builds cleanly
• Ran on a Pixel 10 Pro emulator (API 36/37) with a mock location near Union Square, NYC
• Destination list screen renders all three destinations; tapping one prompts for location permission on first launch
• After granting permission, tapping a destination fetches the current location, calculates a route, and logs the distance to Logcat
• Full-screen navigation view renders correctly: map, maneuver banner, speed limit, etc
• Simulated route replay advances realistically along the calculated route

To test locally

Reviewers will need their own Mapbox tokens:

• A secret token (Downloads:Read scope) in ~/.gradle/gradle.properties as MAPBOX_DOWNLOADS_TOKEN
• A public token in app/src/main/res/values/mapbox_access_token.xml

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