Add gl-text-transform-capitalize CSS util to GitLab UI and use it in ee/app/assets/javascripts/vulnerabilities/components/vulnerability_details.vue

The following discussion from !92933 (closed) should be addressed:

• @pgascouvaillancourt started a discussion:

  note: GitLab UI currently doesn't have a text-capitalize utility. In a follow-up, I'll add that missing utility and apply it here.

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• Add .gl-text-transform-capitalize to GitLab UI.
• [-] Use the new util in ee/app/assets/javascripts/vulnerabilities/components/vulnerability_details.vue (won't do for now, see #368794 (comment 1040420634)).