BUGFIX: Import types and typevars from core #10285

Job	Run time
Python 3.8 extended tests	2m 39s
test with unpublished langchain-core - Python 3.8	50s
Python 3.9 extended tests	2m 41s
Python 3.10 extended tests	2m 37s
test with unpublished langchain-core - Python 3.9	29s
Python 3.11 extended tests	2m 27s
test with unpublished langchain-core - Python 3.10	37s
test with unpublished langchain-core - Python 3.11	48s
compile-integration-tests / Python 3.8	34s
lint / build (3.8)	41s
compile-integration-tests / Python 3.9	45s
lint / build (3.11)	41s
compile-integration-tests / Python 3.10	27s
test / Python 3.8	33s
compile-integration-tests / Python 3.11	29s
test / Python 3.9	41s
test / Python 3.10	37s
test / Python 3.11	35s
pydantic-compatibility / Pydantic v1/v2 compatibility - Python 3.8	33s
pydantic-compatibility / Pydantic v1/v2 compatibility - Python 3.9	39s
pydantic-compatibility / Pydantic v1/v2 compatibility - Python 3.10	43s
pydantic-compatibility / Pydantic v1/v2 compatibility - Python 3.11	33s
	21m 39s

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