feat(client): add validate_structured_output option to ClientSession #2516

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	34s
checks / test (3.12, locked, windows-latest)	1m 25s
checks / test (3.10, locked, ubuntu-latest)	51s
checks / test (3.11, lowest-direct, windows-latest)	1m 17s
checks / test (3.10, lowest-direct, windows-latest)	2m 8s
checks / test (3.12, lowest-direct, windows-latest)	1m 32s
checks / test (3.11, locked, windows-latest)	1m 18s
checks / test (3.11, lowest-direct, ubuntu-latest)	52s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 1s
checks / test (3.13, locked, ubuntu-latest)	43s
checks / test (3.13, lowest-direct, windows-latest)	1m 26s
checks / test (3.10, lowest-direct, ubuntu-latest)	52s
checks / test (3.10, locked, windows-latest)	1m 17s
checks / test (3.11, locked, ubuntu-latest)	45s
checks / test (3.12, locked, ubuntu-latest)	51s
checks / test (3.13, lowest-direct, ubuntu-latest)	51s
checks / test (3.13, locked, windows-latest)	1m 28s
checks / test (3.14, locked, windows-latest)	2m 26s
checks / test (3.14, locked, ubuntu-latest)	1m 46s
checks / test (3.14, lowest-direct, ubuntu-latest)	45s
checks / test (3.14, lowest-direct, windows-latest)	1m 25s
all-green	2s
	25m 46s

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