Swaps sanitize-html for dompurify

What does this MR do?

This MR replaces sanitize-html for the superior DOM Purify.

DOMPurify is considered a more robust sanitizer, despite being 90% smaller than sanitize-html (6.6kb compared to 66.8kb).

This MR does nothing other than swap out the two libraries.

Dependencies that need approval:

dompurify, 2.0.11, "MPL-2.0 OR Apache-2.0"

Next Steps

After this MR is merged, we should look into migrating Gitlab UI to use DOMPurify

Issue - gitlab-ui#905 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• [-] Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team