reset static method
Drops the cached tracker and the persisted user id so the next initializeSnowplowClient builds a new tracker under a fresh id. Without this a logged-out user keeps being tracked under the previous id.
The plugin has no removeTracker; the next createTracker call reuses the
appTracker namespace, which replaces the native tracker.
Implementation
static Future<void> reset() async {
_snowplowClient = null;
_snowplowUserId = null;
await cacheInstance.clearSnowplowUserId();
}