Add vulnerability training urls GraphQL mock data

What does this MR do and why?

Previously, we thought we were going to make the vendor API request via the frontend . After a few long discussions, we have decided the best course is to actually have the backend make the request and act as a service for the frontend to consume it in our GraphQL query. You can see the discussion here > https://gitlab.com/gitlab-org/gitlab/-/issues/349910#note_838068676

The changes to switch over is going to be a bit intensive, so to keeps our MR small, I'm going to tackle this iteratively:

Topic	MR
create mock graphql query	This MR
update logic to use mock graphql query	TBD
implement some sort of polling to work with backend reactive caching	TBD
once BE is completed, switch to use real data	TBD

Here's the proposed schema:

Pending Request	Completed Request

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