Data modification language (DML) operations are generally available (GA)

## Feature Feature [Data modification language (DML) operations](https://docs.cloud.google.com/firestore/native/docs/pipeline/dml)are generally available ([GA](https://cloud.google.com/products#product-launch-stages)). Added support for [insert](https://docs.cloud.google.com/firestore/native/docs/pipeline/stages/output/insert) and [upsert](https://docs.cloud.google.com/firestore/native/docs/pipeline/stages/output/upsert).