Firestore: 'increment' / 'minimum' / 'maximum' field transform attributes

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Here's the log from Synthtool:

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/firestore/synth.py. synthtool > Ensuring dependencies. synthtool > Pulling artman image. latest: Pulling from googleapis/artman Digest: sha256:5a96c2c5c6f9570cc9556b63dc9ce1838777fd9166b5b64e43ad8e0ecee2fe2c Status: Image is up to date for googleapis/artman:latest synthtool > Cloning googleapis. synthtool > Running generator for google/firestore/artman_firestore.yaml. synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/firestore-v1beta1. synthtool > Replaced 'from google.cloud import firestore_v1beta1' in tests/unit/gapic/v1beta1/test_firestore_client_v1beta1.py. synthtool > Replaced 'client = firestore_v1beta1.FirestoreClient' in tests/unit/gapic/v1beta1/test_firestore_client_v1beta1.py. .coveragerc .flake8 MANIFEST.in noxfile.py.j2 setup.cfg Running session blacken Creating virtualenv using python3.6 in /tmpfs/src/git/autosynth/working_repo/firestore/.nox/blacken pip install --upgrade black black google tests docs reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/gapic/enums.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/gapic/transports/firestore_grpc_transport.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/gapic/firestore_client_config.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/common_pb2_grpc.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/common_pb2.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/document_pb2_grpc.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/gapic/firestore_client.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/firestore_pb2_grpc.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/query_pb2_grpc.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/document_pb2.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/write_pb2_grpc.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/query_pb2.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/write_pb2.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/tests/unit/gapic/v1beta1/test_firestore_client_v1beta1.py reformatted /tmpfs/src/git/autosynth/working_repo/firestore/google/cloud/firestore_v1beta1/proto/firestore_pb2.py All done! ✨ 🍰 ✨ 15 files reformatted, 43 files left unchanged. Session blacken was successful. synthtool > Cleaned up 2 temporary directories. synthtool > Wrote metadata to synth.metadata. 

[tseaver]

googleapis sync commit (ignore the v1 files until we update to use them).

[tseaver]

Flaky systest reported in #7130.