Adds stories for namespace and project storage Usage Quotas apps

What does this MR do and why?

Adds storybook stories for ee/usage_quotas/storage/components/namespace_storage_app.vue and ~/usage_quotas/storage/components/project_storage_app.vue, mocking apollo graphql requests.

Main purpose of this MR is to add stories with apollo mocks. Stories need further improvement and should cover more cases. I expect to do that in follow-ups or during working on features for related apps.

I think by creating more fixture generated data, we could cover more edge cases, to be easier tested and presented through stories.

Screenshots or screen recordings

namespace	proejct

How to set up and validate locally

You might need namespace fixtures:

bundle exec rspec ee/spec/frontend/fixtures/namespace.rb
bundle exec rspec spec/frontend/fixtures/projects.rb

After generating fixtures — start storybook:

npm run storybook:start

And open http://localhost:9002/?path=/story/usage-quotas-storage-project-storage-app and http://localhost:9002/?path=/story/ee-usage-quotas-storage-namespace-storage-app

MR acceptance checklist

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