feat: Add embed_meta_fields to Ranker nodes

[sjrl]

Related Issues

• fixes #5354

Proposed Changes:

Adds the option embed_meta_fields to the Ranker nodes using a similar implementation to the one used in EmbeddingRetrievers.

How did you test it?

Added a new unit test.

Notes for the reviewer

This feature is complete, but I would like to test it out on some data first to see how well it performs.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue