add telem current location engine being used track support (#605)

Author: Guardiola31337

mapbox/libandroid-telemetry/src/main/java/com/mapbox/services/android/telemetry/MapboxTelemetry.java

@@ -795,4 +795,12 @@ private Object addSdkVersion() {
 
     return sdkVersion;
   }
+
+  // For internal use only
+  // This is an experimental API. Experimental APIs are quickly evolving and
+  // might change or be removed in minor versions.
+  @Experimental
+  public void addLocationEngineName(@NonNull String locationEngineName, Hashtable<String, Object> eventWithAttributes) {
+    eventWithAttributes.put(MapboxNavigationEvent.KEY_LOCATION_ENGINE, locationEngineName);
+  }
 }

mapbox/libandroid-telemetry/src/main/java/com/mapbox/services/android/telemetry/http/TelemetryClient.java

@@ -210,6 +210,7 @@ private void sendEventsWrapped(Vector<Hashtable<String, Object>> events, Callbac
         evt.get(MapboxNavigationEvent.KEY_ARRIVAL_TIMESTAMP));
       jsonObject.putOpt(MapboxNavigationEvent.KEY_STEP, evt.get(MapboxNavigationEvent.KEY_STEP));
       jsonObject.putOpt(MapboxNavigationEvent.KEY_STEP_COUNT, evt.get(MapboxNavigationEvent.KEY_STEP_COUNT));
+      jsonObject.putOpt(MapboxNavigationEvent.KEY_LOCATION_ENGINE, evt.get(MapboxNavigationEvent.KEY_LOCATION_ENGINE));
 
       // Step metadata
       jsonObject.putOpt(MapboxNavigationEvent.KEY_UPCOMING_INSTRUCTION,

mapbox/libandroid-telemetry/src/main/java/com/mapbox/services/android/telemetry/navigation/MapboxNavigationEvent.java

@@ -72,6 +72,7 @@ public class MapboxNavigationEvent {
   public static final String KEY_ARRIVAL_TIMESTAMP = "arrivalTimestamp";
   public static final String KEY_STEP = "step";
   public static final String KEY_STEP_COUNT = "stepCount";
+  public static final String KEY_LOCATION_ENGINE = "locationEngine";
 
   // Step metadata
   public static final String KEY_UPCOMING_INSTRUCTION = "upcomingInstruction";