Eventarc support for creating triggers for direct events from Cloud Firestore is generally available (GA)

## Feature Eventarc support for [creating triggers](https://cloud.google.com/eventarc/docs/targets#triggers) for direct events from [Cloud Firestore](https://cloud.google.com/eventarc/docs/event-types#cloud-firestore) is generally available ([GA](https://cloud.google.com/products#product-launch-stages)).