Add rich text editor in vulnerabilities

What does this MR do and why?

Add rich text editor in vulnerabilities

Allow using rich text editor when creating/editing vulnerabilities and solutions.

Changelog: added

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Vulnerability description	Vulnerability solution

How to set up and validate locally

1. In project sidebar, go to Secure > Vulnerability report
2. Click + Submit vulnerability.
3. Notice that the vulnerability description box on the top and the solution description box at the bottom now supports rich text editor.

Related to #407491 (closed)