INTPYTHON-832 Add search_by_vector method to VectorStore

[barnuri]

This pull request adds a new method to the VectorStore class in vectorstores.py, enhancing its functionality to support similarity search directly by vector input.

New functionality:

• Added the similarity_search_by_vector method to the VectorStore class, allowing users to perform similarity searches using a query vector and returning relevant documents.

[blink1073]

Hi @barnuri, thanks again for this PR! Can you please add a test for this new method to https://github.com/langchain-ai/langchain-mongodb/blob/main/libs/langchain-mongodb/tests/integration_tests/test_vectorstore_from_texts.py?

[caseyclements]

Hi @barnuri. Just curious. Even though _similarity_search_with_score is marked for internal use by its leading underscore, what motivated you not to use it?

[barnuri]

Hi @barnuri. Just curious. Even though _similarity_search_with_score is marked for internal use by its leading underscore, what motivated you not to use it?

we have a logic that already have the vector, and tried multiple searches, so embedded it every time instead of passing the vector its a waste