Add usage events to user dashboard

What does this MR do and why?

Adds usage events table to Usage Billing User dashboard

References

• Resolves to #566205

Screenshots or screen recordings

See !205107 (comment 2752167142)

How to set up and validate locally

To test it on GDK:

• Ensure you're running GitLab as self-managed (e.g. export GITLAB_SIMULATE_SAAS=0 gdk restart\)
• Ensure you've a license added to your instance
• Enable usage_billing_dev feature flag (e.g. http://localhost:3000/rails/features/usage_billing_dev)
• Navigate to the /admin/gitlab_duo/usage/users/42
• Ensure the page is rendered as on the screenshots

To test on storybook:

• Start storybook (e.g. yarn storybook:start)
• Open Storybook on http://localhost:6006/?path=/story/ee-usage-quotas-usage-billing-users-show-app--default

MR acceptance checklist

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