[DNM] (lib) vLLM-backed embedder experimentation

[charlesbluca]

Description

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• If adjusting docker-compose.yaml environment variables have you ensured those are mimicked in the Helm values.yaml file.

[charlesbluca]

This branch has gotten messy with experimentation work - moving the actual feature add to #1494