Create the vulnerability StatusBadge component

What does this MR do and why?

Abstracts some logic from the vulnerability header component into a reusable StatusBadge component that we'll be able to render the status in the pipeline vulnerability modal.

Screenshots or screen recordings

No visual change, we are only abstracting existing code to make it more reusable. Here's how the badge looks like though:

How to set up and validate locally

In the GDK

1. Navigate to a project that has some vulnerabilities.
2. From the Security & Compliance > Vulnerability report page, click on any vulnerability.
3. Change the vulnerability's status in the Status dropdown to see all of the possible variants.

In Storybook

Alternatively, you can start Storybook by running yarn storybook:start. The component is demoed in the ee/vue_shared/security_reports/components/status_badge story.

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.

Related to #368933 (closed)