community[minor]: Add QuantizedEmbedders (#17391)

**Description:** 
* adding Quantized embedders using optimum-intel and
intel-extension-for-pytorch.
* added mdx documentation and example notebooks 
* added embedding import testing.

**Dependencies:** 
optimum = {extras = ["neural-compressor"], version = "^1.14.0", optional
= true}
intel_extension_for_pytorch = {version = "^2.2.0", optional = true}

Dependencies have been added to pyproject.toml for the community lib.  

**Twitter handle:** @peter_izsak

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/embeddings/__init__.py

@@ -71,6 +71,7 @@ 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
+from langchain_community.embeddings.optimum_intel import QuantizedBiEncoderEmbeddings
 from langchain_community.embeddings.sagemaker_endpoint import (
     SagemakerEndpointEmbeddings,
 )
@@ -149,6 +150,7 @@ __all__ = [
     "BookendEmbeddings",
     "VolcanoEmbeddings",
     "OCIGenAIEmbeddings",
+    "QuantizedBiEncoderEmbeddings",
     "NeMoEmbeddings",
 ]