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/tests/integration_tests/embeddings/test_vertexai.py

@@ -0,0 +1,42 @@
+"""Test Vertex AI API wrapper.
+In order to run this test, you need to install VertexAI SDK 
+pip install google-cloud-aiplatform>=1.35.0
+
+Your end-user credentials would be used to make the calls (make sure you've run 
+`gcloud auth login` first).
+"""
+from langchain_community.embeddings import VertexAIEmbeddings
+
+
+def test_embedding_documents() -> None:
+    documents = ["foo bar"]
+    model = VertexAIEmbeddings()
+    output = model.embed_documents(documents)
+    assert len(output) == 1
+    assert len(output[0]) == 768
+    assert model.model_name == model.client._model_id
+
+
+def test_embedding_query() -> None:
+    document = "foo bar"
+    model = VertexAIEmbeddings()
+    output = model.embed_query(document)
+    assert len(output) == 768
+
+
+def test_paginated_texts() -> None:
+    documents = [
+        "foo bar",
+        "foo baz",
+        "bar foo",
+        "baz foo",
+        "bar bar",
+        "foo foo",
+        "baz baz",
+        "baz bar",
+    ]
+    model = VertexAIEmbeddings()
+    output = model.embed_documents(documents)
+    assert len(output) == 8
+    assert len(output[0]) == 768
+    assert model.model_name == model.client._model_id