Add new langchain vectorstore models

[lrafeei]

Overview

This PR adds the following vectorstore models to Langchain: 'DuckDB', 'EcloudESVectorStore', 'InMemoryVectorStore', 'PathwayVectorClient', 'VDMS'

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ PYTHON	bandit	2		0	5.32s
✅ PYTHON	black	2	0	0	1.68s
✅ PYTHON	flake8	2		0	0.88s
✅ PYTHON	isort	2	0	0	0.21s
✅ PYTHON	pylint	2		0	7.85s

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