Add LangGraph workflow streams sample #1268

Job	Run time
build-lint-test (3.10, ubuntu-latest)	6m 15s
build-lint-test (3.10, macos-arm)	8m 16s
build-lint-test (3.10, macos-intel)	10m 45s
build-lint-test (3.14, ubuntu-latest)	6m 26s
build-lint-test (3.10, windows-latest)	7m 19s
build-lint-test (3.14, macos-arm)	6m 8s
build-lint-test (3.14, macos-intel)	8m 25s
build-lint-test (3.14, windows-latest)	7m 38s
	1h 1m 12s

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