* Reformat sdk only using the new yapf config.
* Reformat docstrings using docformatter.
* update golden files to resolve diff caused by whitespaces
* fix some tests
* format .py files under sdk/python/tests using yapf
* additional docformatter
* fix some tests
* Configure gcp connectors in dsl
* Make configure_gcp_connector more extensible
* Add add_pod_env op handler.
* Only apply add_pod_env on ContainerOp
* Update license header