chore: make icon verification more robust

[brian-smith-tcril]

Description

• This ensures we check that only icons generated from svgs are checked in.
• CI on this will fail until fix: remove duplicate icons #3035 is merged and this is rebased

Merge Checklist

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Post-merge Checklist

• Verify your changes were released to NPM at the expected version.
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• 🎉 🙌 Celebrate! Thanks for your contribution.

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[arbrandes]

LGTM! Let's just have a rebase to make sure the CI isn´t failing.

[openedx-semantic-release-bot]

🎉 This PR is included in version 22.3.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀