feat: Add TelemetryNavigationCallbacks implementation

Author: buongarzoni

rollbar-android/src/main/java/com/rollbar/android/TelemetryNavigationCallbacks.java

@@ -0,0 +1,52 @@
+package com.rollbar.android;
+
+import android.app.Activity;
+import android.app.Application;
+import android.os.Bundle;
+
+import com.rollbar.api.payload.data.Level;
+import com.rollbar.api.payload.data.Source;
+import com.rollbar.notifier.telemetry.TelemetryEventTracker;
+
+class TelemetryNavigationCallbacks implements Application.ActivityLifecycleCallbacks {
+    private final TelemetryEventTracker telemetryEventTracker;
+    private String lastActivity;
+
+    TelemetryNavigationCallbacks(TelemetryEventTracker telemetryEventTracker) {
+        this.telemetryEventTracker = telemetryEventTracker;
+    }
+
+    @Override
+    public void onActivityResumed(Activity activity) {
+        String current = activity.getClass().getSimpleName();
+
+        if (lastActivity != null && !lastActivity.equals(current)) {
+            telemetryEventTracker.recordNavigationEventFor(
+                Level.INFO,
+                Source.CLIENT,
+                lastActivity,
+                current
+            );
+        }
+
+        lastActivity = current;
+    }
+
+    @Override
+    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {}
+
+    @Override
+    public void onActivityStarted(Activity activity) {}
+
+    @Override
+    public void onActivityPaused(Activity activity) {}
+
+    @Override
+    public void onActivityStopped(Activity activity) {}
+
+    @Override
+    public void onActivitySaveInstanceState(Activity activity, Bundle outState) {}
+
+    @Override
+    public void onActivityDestroyed(Activity activity) {}
+}