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/utils/openai_functions.py

@@ -1,51 +1,15 @@
-from typing import Literal, Optional, Type, TypedDict
+# these stubs are just for backwards compatibility
 
-from langchain_core.pydantic_v1 import BaseModel
-from langchain_core.utils.json_schema import dereference_refs
+from langchain_core.utils.function_calling import (
+    FunctionDescription,
+    ToolDescription,
+    convert_pydantic_to_openai_function,
+    convert_pydantic_to_openai_tool,
+)
 
-
-class FunctionDescription(TypedDict):
-    """Representation of a callable function to the OpenAI API."""
-
-    name: str
-    """The name of the function."""
-    description: str
-    """A description of the function."""
-    parameters: dict
-    """The parameters of the function."""
-
-
-class ToolDescription(TypedDict):
-    """Representation of a callable function to the OpenAI API."""
-
-    type: Literal["function"]
-    function: FunctionDescription
-
-
-def convert_pydantic_to_openai_function(
-    model: Type[BaseModel],
-    *,
-    name: Optional[str] = None,
-    description: Optional[str] = None,
-) -> FunctionDescription:
-    """Converts a Pydantic model to a function description for the OpenAI API."""
-    schema = dereference_refs(model.schema())
-    schema.pop("definitions", None)
-    return {
-        "name": name or schema["title"],
-        "description": description or schema["description"],
-        "parameters": schema,
-    }
-
-
-def convert_pydantic_to_openai_tool(
-    model: Type[BaseModel],
-    *,
-    name: Optional[str] = None,
-    description: Optional[str] = None,
-) -> ToolDescription:
-    """Converts a Pydantic model to a function description for the OpenAI API."""
-    function = convert_pydantic_to_openai_function(
-        model, name=name, description=description
-    )
-    return {"type": "function", "function": function}
+__all__ = [
+    "FunctionDescription",
+    "ToolDescription",
+    "convert_pydantic_to_openai_function",
+    "convert_pydantic_to_openai_tool",
+]