Add missing webUrl in Work Item

What does this MR do and why?

We are getting following error while adding any Objective/Key result/Task to Child items widget.

This might be due to webUrl attribute added to WorkItemWidgetLinkedItems.workItem.webUrl but not the actual WorkItem object in work_items/graphql/work_item.fragment.graphql#L4. There is no impact on functionality but it can cause issues while writing cache.

Screenshots or screen recordings

No visual changes

How to set up and validate locally

Prerequisites:

1. Enable the OKRs feature as mentioned in the OKRs docs (e.g. ::Feature.enabled?(:okrs_mvc, Project.find(<PROJECT_ID>)) and the namespace must have Ultimate plan).

Steps to verify:

1. Login with any user
2. Go to any Project > Issues > List
3. Create an new Objective under New issue split button
4. Go to Objective detail page
5. Add a new Objective or Key result under Child Items section
6. Check if there are no errors related to Missing field 'webUrl' while writing result in browser console.

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.