IoT: Add 'client_options' support, update list method docstrings (via synth).

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Here's the log from Synthtool:

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/iot/synth.py. synthtool > Ensuring dependencies. synthtool > Pulling artman image. latest: Pulling from googleapis/artman Digest: sha256:45263333b058a4b3c26a8b7680a2710f43eae3d250f791a6cb66423991dcb2df Status: Image is up to date for googleapis/artman:latest synthtool > Cloning googleapis. synthtool > Running generator for google/cloud/iot/artman_cloudiot.yaml. synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/iot-v1. synthtool > Copy: /home/kbuilder/.cache/synthtool/googleapis/google/cloud/iot/v1/resources.proto to /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/iot-v1/google/cloud/iot_v1/proto/resources.proto synthtool > Copy: /home/kbuilder/.cache/synthtool/googleapis/google/cloud/iot/v1/device_manager.proto to /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/iot-v1/google/cloud/iot_v1/proto/device_manager.proto synthtool > Placed proto files into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/python/iot-v1/google/cloud/iot_v1/proto. .coveragerc .flake8 MANIFEST.in noxfile.py.j2 setup.cfg Running session blacken Creating virtualenv using python3.6 in .nox/blacken pip install black black docs google tests noxfile.py setup.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/__init__.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/gapic/enums.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/gapic/device_manager_client_config.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/docs/conf.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/gapic/transports/device_manager_grpc_transport.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/proto/device_manager_pb2_grpc.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/proto/resources_pb2_grpc.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/types.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/noxfile.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/tests/system/gapic/v1/test_system_device_manager_v1.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/gapic/device_manager_client.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/tests/unit/gapic/v1/test_device_manager_client_v1.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/proto/device_manager_pb2.py reformatted /tmpfs/src/git/autosynth/working_repo/iot/google/cloud/iot_v1/proto/resources_pb2.py All done! ✨ 🍰 ✨ 14 files reformatted, 7 files left unchanged. Session blacken was successful. synthtool > Cleaned up 2 temporary directories. synthtool > Wrote metadata to synth.metadata. 

[tseaver]

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