[FEATURE] Allow selection of custom embedding model

[Rickyneer]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Problem/Usecase Description

It would be nice if users could select their own embedding (and reranker) model to get better performance.

Proposed Solution

By allowing to select a configured model to be selected as embed model.

Feature Type

New functionality

Additional Context

No response

Contribution

• I'd be willing to implement this feature
• I'd be willing to test this feature once implemented
• I can provide additional details or clarification if needed