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/utils/math.py

@@ -0,0 +1,75 @@
+"""Math utils."""
+import logging
+from typing import List, Optional, Tuple, Union
+
+import numpy as np
+
+logger = logging.getLogger(__name__)
+
+Matrix = Union[List[List[float]], List[np.ndarray], np.ndarray]
+
+
+def cosine_similarity(X: Matrix, Y: Matrix) -> np.ndarray:
+    """Row-wise cosine similarity between two equal-width matrices."""
+    if len(X) == 0 or len(Y) == 0:
+        return np.array([])
+
+    X = np.array(X)
+    Y = np.array(Y)
+    if X.shape[1] != Y.shape[1]:
+        raise ValueError(
+            f"Number of columns in X and Y must be the same. X has shape {X.shape} "
+            f"and Y has shape {Y.shape}."
+        )
+    try:
+        import simsimd as simd
+
+        X = np.array(X, dtype=np.float32)
+        Y = np.array(Y, dtype=np.float32)
+        Z = 1 - simd.cdist(X, Y, metric="cosine")
+        if isinstance(Z, float):
+            return np.array([Z])
+        return Z
+    except ImportError:
+        logger.info(
+            "Unable to import simsimd, defaulting to NumPy implementation. If you want "
+            "to use simsimd please install with `pip install simsimd`."
+        )
+        X_norm = np.linalg.norm(X, axis=1)
+        Y_norm = np.linalg.norm(Y, axis=1)
+        # Ignore divide by zero errors run time warnings as those are handled below.
+        with np.errstate(divide="ignore", invalid="ignore"):
+            similarity = np.dot(X, Y.T) / np.outer(X_norm, Y_norm)
+        similarity[np.isnan(similarity) | np.isinf(similarity)] = 0.0
+        return similarity
+
+
+def cosine_similarity_top_k(
+    X: Matrix,
+    Y: Matrix,
+    top_k: Optional[int] = 5,
+    score_threshold: Optional[float] = None,
+) -> Tuple[List[Tuple[int, int]], List[float]]:
+    """Row-wise cosine similarity with optional top-k and score threshold filtering.
+
+    Args:
+        X: Matrix.
+        Y: Matrix, same width as X.
+        top_k: Max number of results to return.
+        score_threshold: Minimum cosine similarity of results.
+
+    Returns:
+        Tuple of two lists. First contains two-tuples of indices (X_idx, Y_idx),
+            second contains corresponding cosine similarities.
+    """
+    if len(X) == 0 or len(Y) == 0:
+        return [], []
+    score_array = cosine_similarity(X, Y)
+    score_threshold = score_threshold or -1.0
+    score_array[score_array < score_threshold] = 0
+    top_k = min(top_k or len(score_array), np.count_nonzero(score_array))
+    top_k_idxs = np.argpartition(score_array, -top_k, axis=None)[-top_k:]
+    top_k_idxs = top_k_idxs[np.argsort(score_array.ravel()[top_k_idxs])][::-1]
+    ret_idxs = np.unravel_index(top_k_idxs, score_array.shape)
+    scores = score_array.ravel()[top_k_idxs].tolist()
+    return list(zip(*ret_idxs)), scores  # type: ignore