Add FE support to use namespace queries

What does this MR do and why?

This MR covers FE changes to fix empty projects list in group level work_items in modal.

Proposed solution: #470371 (comment 1983029667)

Issue: #470371 (closed)

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Before	After

How to set up and validate locally

To test this locally, you need to enable WI at group level, so you will have to enable these feature flags namespace_level_work_items (If you are still unable to access work-item page for an epic then enable/disable FF from this list - &11777 )

1. Visit Epics page and try to create a new EPIC(If all relevant FF's are enabled then you should see a modal when you click on New Epic)
2. Open the newly created epic and replace epics in the URL with work_items, SO the target URL would be something like http://127.0.0.1:3000/groups/flightjs/-/work_items/6
3. create few child issues
4. Open a child issue, it should open in a modal
5. Click on Add Task and click on New Task , you should see projects populated in the dropdown