openai[minor]: implement langchain-openai package (#15503)

Todo

- [x] copy over integration tests
- [x] update docs with new instructions in #15513 
- [x] add linear ticket to bump core -> community, community->langchain,
and core->openai deps
- [ ] (optional): add `pip install langchain-openai` command to each
notebook using it
- [x] Update docstrings to not need `openai` install
- [x] Add serialization
- [x] deprecate old models

Contributor steps:

- [x] Add secret names to manual integrations workflow in
.github/workflows/_integration_test.yml
- [x] Add secrets to release workflow (for pre-release testing) in
.github/workflows/_release.yml

Maintainer steps (Contributors should not do these):

- [x] set up pypi and test pypi projects
- [x] add credential secrets to Github Actions
- [ ] add package to conda-forge


Functional changes to existing classes:

- now relies on openai client v1 (1.6.1) via concrete dep in
langchain-openai package

Codebase organization

- some function calling stuff moved to
`langchain_core.utils.function_calling` in order to be used in both
community and langchain-openai

libs/community/langchain_community/embeddings/openai.py

@@ -19,6 +19,7 @@ from typing import (
 )
 
 import numpy as np
+from langchain_core._api.deprecation import deprecated
 from langchain_core.embeddings import Embeddings
 from langchain_core.pydantic_v1 import BaseModel, Extra, Field, root_validator
 from langchain_core.utils import get_from_dict_or_env, get_pydantic_field_names
@@ -137,6 +138,11 @@ async def async_embed_with_retry(embeddings: OpenAIEmbeddings, **kwargs: Any) ->
     return await _async_embed_with_retry(**kwargs)
 
 
+@deprecated(
+    since="0.1.0",
+    removal="0.2.0",
+    alternative="langchain_openai.OpenAIEmbeddings",
+)
 class OpenAIEmbeddings(BaseModel, Embeddings):
     """OpenAI embedding models.