Add `ai_resource` to the ApplicationContext

What does this MR do and why?

As a part of the ChatBot improvements, we should provide a resource_id to the ChatBot, to improve the current workflow.

In this MR, we are expanding the ApplicationContext with a new value:

ai_resource: issuable.to_global_id

In the follow-up MR, we would use ai_resource for the ChatBot.

Screenshots or screen recordings

N/A

Before	After

How to set up and validate locally

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #415490 (closed)