community[major], core[patch], langchain[patch], experimental[patch]: Create langchain-community (#14463)

Moved the following modules to new package langchain-community in a backwards compatible fashion:

```
mv langchain/langchain/adapters community/langchain_community
mv langchain/langchain/callbacks community/langchain_community/callbacks
mv langchain/langchain/chat_loaders community/langchain_community
mv langchain/langchain/chat_models community/langchain_community
mv langchain/langchain/document_loaders community/langchain_community
mv langchain/langchain/docstore community/langchain_community
mv langchain/langchain/document_transformers community/langchain_community
mv langchain/langchain/embeddings community/langchain_community
mv langchain/langchain/graphs community/langchain_community
mv langchain/langchain/llms community/langchain_community
mv langchain/langchain/memory/chat_message_histories community/langchain_community
mv langchain/langchain/retrievers community/langchain_community
mv langchain/langchain/storage community/langchain_community
mv langchain/langchain/tools community/langchain_community
mv langchain/langchain/utilities community/langchain_community
mv langchain/langchain/vectorstores community/langchain_community
mv langchain/langchain/agents/agent_toolkits community/langchain_community
mv langchain/langchain/cache.py community/langchain_community
mv langchain/langchain/adapters community/langchain_community
mv langchain/langchain/callbacks community/langchain_community/callbacks
mv langchain/langchain/chat_loaders community/langchain_community
mv langchain/langchain/chat_models community/langchain_community
mv langchain/langchain/document_loaders community/langchain_community
mv langchain/langchain/docstore community/langchain_community
mv langchain/langchain/document_transformers community/langchain_community
mv langchain/langchain/embeddings community/langchain_community
mv langchain/langchain/graphs community/langchain_community
mv langchain/langchain/llms community/langchain_community
mv langchain/langchain/memory/chat_message_histories community/langchain_community
mv langchain/langchain/retrievers community/langchain_community
mv langchain/langchain/storage community/langchain_community
mv langchain/langchain/tools community/langchain_community
mv langchain/langchain/utilities community/langchain_community
mv langchain/langchain/vectorstores community/langchain_community
mv langchain/langchain/agents/agent_toolkits community/langchain_community
mv langchain/langchain/cache.py community/langchain_community
```

Moved the following to core
```
mv langchain/langchain/utils/json_schema.py core/langchain_core/utils
mv langchain/langchain/utils/html.py core/langchain_core/utils
mv langchain/langchain/utils/strings.py core/langchain_core/utils
cat langchain/langchain/utils/env.py >> core/langchain_core/utils/env.py
rm langchain/langchain/utils/env.py
```

See .scripts/community_split/script_integrations.sh for all changes

libs/community/langchain_community/document_loaders/parsers/language/python.py

@@ -0,0 +1,51 @@
+import ast
+from typing import Any, List
+
+from langchain_community.document_loaders.parsers.language.code_segmenter import (
+    CodeSegmenter,
+)
+
+
+class PythonSegmenter(CodeSegmenter):
+    """Code segmenter for `Python`."""
+
+    def __init__(self, code: str):
+        super().__init__(code)
+        self.source_lines = self.code.splitlines()
+
+    def is_valid(self) -> bool:
+        try:
+            ast.parse(self.code)
+            return True
+        except SyntaxError:
+            return False
+
+    def _extract_code(self, node: Any) -> str:
+        start = node.lineno - 1
+        end = node.end_lineno
+        return "\n".join(self.source_lines[start:end])
+
+    def extract_functions_classes(self) -> List[str]:
+        tree = ast.parse(self.code)
+        functions_classes = []
+
+        for node in ast.iter_child_nodes(tree):
+            if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef, ast.ClassDef)):
+                functions_classes.append(self._extract_code(node))
+
+        return functions_classes
+
+    def simplify_code(self) -> str:
+        tree = ast.parse(self.code)
+        simplified_lines = self.source_lines[:]
+
+        for node in ast.iter_child_nodes(tree):
+            if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef, ast.ClassDef)):
+                start = node.lineno - 1
+                simplified_lines[start] = f"# Code for: {simplified_lines[start]}"
+
+                assert isinstance(node.end_lineno, int)
+                for line_num in range(start + 1, node.end_lineno):
+                    simplified_lines[line_num] = None  # type: ignore
+
+        return "\n".join(line for line in simplified_lines if line is not None)