Expose uuid on VulnerabilityType

What does this MR do and why?

Expose uuid on VulnerabilityType. This will allow finding uuids to be retrieved via GraphQL.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. If your GDK does not have vulnerabilities, run bundle exec rake 'gitlab:seed:vulnerabilities'

2. Go to <instance_url>/-/graphql-explorer

3. Run this query:

   {
     vulnerability(id: "gid://gitlab/Vulnerability/1") {
       id
       uuid
       description
     }
   }

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.