[FEATURE] Support for PostgreSQL as a Vector Store in LlamaIndex

[seonghobae]

Describe the feature you'd like
Hey there, Flowise team! 😊 I've been exploring the capabilities of LlamaIndex and it's been an awesome journey so far. However, I noticed that we currently don't have support for using PostgreSQL as a vector store within LlamaIndex. It would be fantastic if we could integrate PostgreSQL, as it's widely used for its robustness and reliability. This feature would be a great addition for those of us who prefer PostgreSQL and wish to leverage its capabilities for vector storage.

Additional context
Many projects and companies rely on PostgreSQL for their database needs, and having the ability to use it as a vector store directly within LlamaIndex would streamline processes and maintain consistency across different parts of our tech stack. Plus, PostgreSQL's advanced indexing features could be beneficial for optimizing vector search performance.

Best,
Seongho Bae