feat(vectorstores): add Bedrock Knowledge Bases vectorstore support

[lucaronca]

Description

Support AWS Bedrock Knowledge Bases as a vector store, leveraging the Knowledge Bases API.

• Retrieval: Utilizes the Bedrock Knowledge Base API to enable vector-based document retrieval. Documents filtering based on metatag values is also supported.
• Documents Storage: Documents are stored on Knowledge Base Data Sources using S3 as the data source. The strategy to add the documents is: put the documents on the S3 bucket specified by the data source, add the documents to the knowledge base, finally start the ingestion process and wait for it to be completed.

Knowledge Bases as retriever is already supported by python langchain

PR Checklist

• [x] Read the Contributing documentation.
• [x] Read the Code of conduct documentation.
• [x] Name your Pull Request title clearly, concisely, and prefixed with the name of the primarily affected package you changed according to Good commit messages (such as memory: add interfaces for X, Y or util: add whizzbang helpers).
• [x] Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• [x] Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. Fixes #123).
• [x] Describes the source of new concepts.
• [x] References existing implementations as appropriate.
• [x] Contains test coverage for new functions.
• [ ] Passes all golangci-lint checks.