community[minor]: Add OCI Generative AI integration (#16548)

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- **Description:** Adding Oracle Cloud Infrastructure Generative AI
integration. Oracle Cloud Infrastructure (OCI) Generative AI is a fully
managed service that provides a set of state-of-the-art, customizable
large language models (LLMs) that cover a wide range of use cases, and
which is available through a single API. Using the OCI Generative AI
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host your own fine-tuned custom models based on your own data on
dedicated AI clusters.
https://docs.oracle.com/en-us/iaas/Content/generative-ai/home.htm
  - **Issue:** None,
  - **Dependencies:** OCI Python SDK,
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---------

Co-authored-by: Arthur Cheng <arthur.cheng@oracle.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/embeddings/__init__.py

@@ -65,6 +65,7 @@ from langchain_community.embeddings.mlflow_gateway import MlflowAIGatewayEmbeddi
 from langchain_community.embeddings.modelscope_hub import ModelScopeEmbeddings
 from langchain_community.embeddings.mosaicml import MosaicMLInstructorEmbeddings
 from langchain_community.embeddings.nlpcloud import NLPCloudEmbeddings
+from langchain_community.embeddings.oci_generative_ai import OCIGenAIEmbeddings
 from langchain_community.embeddings.octoai_embeddings import OctoAIEmbeddings
 from langchain_community.embeddings.ollama import OllamaEmbeddings
 from langchain_community.embeddings.openai import OpenAIEmbeddings
@@ -144,6 +145,7 @@ __all__ = [
     "VoyageEmbeddings",
     "BookendEmbeddings",
     "VolcanoEmbeddings",
+    "OCIGenAIEmbeddings",
 ]