Draft: Allow additional context to pass through to aigw

What does this MR do and why?

Related to !161898

This MR works together with gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!1194

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

demo_2_thru_rails_monolith

How to set up and validate locally

1. TODO
2. Need to rebase or figure out why there are 600+ changes. There should only be 3 additional minor changes on top of the changes in !161898