[Feature Request]: Add GCP Firestore IO connector for Python SDK

[Luiscri]

What would you like to happen?

Similar to how the Kafka cross-language transform was built, it would be really helpful if Firestore IO connector was made available in Python SDK by using the Java connector through a external transform.

I tried doing it myself but I wasn't able, so having this connector available in the beam package would help many non-advanced users like me to use Firestore as a sink

Issue Priority

Priority: 2 (default / most feature requests should be filed as P2)

Issue Components

• Component: Python SDK
• Component: Java SDK
• Component: Go SDK
• Component: Typescript SDK
• Component: IO connector
• Component: Beam YAML
• Component: Beam examples
• Component: Beam playground
• Component: Beam katas
• Component: Website
• Component: Infrastructure
• Component: Spark Runner
• Component: Flink Runner
• Component: Samza Runner
• Component: Twister2 Runner
• Component: Hazelcast Jet Runner
• Component: Google Cloud Dataflow Runner

[Abacn]

Python SDK currently does not support FirestoreIO. There is a DatastoreIO (apache_beam/io/gcp/datastore/v1new/datastoreio.py) that existed while ago, could be helpful if your Firestore use case supports Datastore mode API