Clickhouse based Vector Store
Labels: name: enhancement, name: lgtm

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#### Description

This PR is mainly to integrate open source version of ClickHouse as Vector Store as it is easy for both local development and adoption of LangChain for enterprises who already have large scale clickhouse deployment.

ClickHouse is a open source real-time OLAP database with full SQL support and a wide range of functions to assist users in writing analytical queries. Some of these functions and data structures perform distance operations between vectors, [enabling ClickHouse to be used as a vector database](https://clickhouse.com/blog/vector-search-clickhouse-p1).  Recently added ClickHouse capabilities like [Approximate Nearest Neighbour (ANN) indices](https://clickhouse.com/docs/en/engines/table-engines/mergetree-family/annindexes) support faster approximate matching of vectors and provide a promising development aimed to further enhance the vector matching capabilities of ClickHouse. 

In LangChain, some ClickHouse based commercial variant vector stores like [Chroma](https://github.com/hwchase17/langchain/blob/master/langchain/vectorstores/chroma.py) and [MyScale](https://github.com/hwchase17/langchain/blob/master/langchain/vectorstores/myscale.py), etc are already integrated, but for some enterprises with large scale Clickhouse clusters deployment, it will be more straightforward to upgrade existing clickhouse infra instead of moving to another similar vector store solution, so we believe it's a valid requirement to integrate open source version of ClickHouse as vector store.

As `clickhouse-connect` is already included by other integrations, this PR won't include any new dependencies. 

#### Before submitting

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1. Added a test for the integration:  https://github.com/haoch/langchain/blob/clickhouse/tests/integration_tests/vectorstores/test_clickhouse.py
2. Added an example notebook and document showing its use: 
   * Notebook: https://github.com/haoch/langchain/blob/clickhouse/docs/modules/indexes/vectorstores/examples/clickhouse.ipynb
   * Doc: https://github.com/haoch/langchain/blob/clickhouse/docs/integrations/clickhouse.md

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etc:

https://github.com/hwchase17/langchain/blob/master/.github/CONTRIBUTING.md
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1. Added a test for the integration:  https://github.com/haoch/langchain/blob/clickhouse/tests/integration_tests/vectorstores/test_clickhouse.py
2. Added an example notebook and document showing its use: 
   * Notebook: https://github.com/haoch/langchain/blob/clickhouse/docs/modules/indexes/vectorstores/examples/clickhouse.ipynb
   * Doc: https://github.com/haoch/langchain/blob/clickhouse/docs/integrations/clickhouse.md


#### Who can review?

Tag maintainers/contributors who might be interested:

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@hwchase17 @dev2049 Could you please help review?