fix: override DOMPurify to patched version

[sbouchet]

What does this PR do?

This PR fixes CVE-2026-49978

DOMPurify version is updated to 3.4.12

What issues does this PR fix?

https://redhat.atlassian.net/browse/CRW-11874

How to test this PR?

Does this PR contain changes that override default upstream Code-OSS behavior?

• the PR contains changes in the code folder (you can skip it if your changes are placed in a che extension )
• the corresponding items were added to the CHANGELOG.md file
• rules for automatic git rebase were added to the .rebase folder

[github-actions]

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[github-actions]

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