…value store implementation (#186)

* feat: add AsyncBigtableVectorStore Class for the async-only vector value store implementation

This commit adds the async-only vector store class that handles the underlying data operations for the main vector store class along with its test files.

* fix: include comments on the key-value store usage cells

Included comments explaining how the embedding cache key-value store works.

* fix: include comments on the key-value store usage cells

Included comments explaining how the embedding cache key-value store works.

* fix: header date for async_vector_store.py

fix: include comments on the key-value store usage cells

Included comments explaining how the embedding cache key-value store works.

* fix: typing for tests and async vector store class

fix: add os environment function for the tests

* fix: isort for imports for test files

* fix: revert removed test_async_key_value_store.py file.

* fix: address PR comments

* fix: address PR comments

* fix: address PR comments

* fix: address PR comments

* fix: address PR comments

* fix: address PR comments

* fix: address PR comments

* fix: add check to make sure each document has an ID.

…gration (#189)

* feat: add `BigtableVectorStore` class for Bigtable <> LangChain Vector Store integration.

* feat: add `BigtableVectorStore` class for Bigtable <> LangChain Vector Store integration.

* fix: isort imports for test file.

* fix: fixture return types.

* chore: add more test cases

* fix: remove await from sync store test suite

* fix: reformat test_vector_store.py

* fix: address PR comments.

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