fix(markdown): copying html into markdown

[hip3r]

closes #7233

Summary

When pasting html into markdown, keep styles instead of plain text. Code copied from official example https://github.com/ianstormtaylor/slate/blob/main/site/examples/ts/paste-html.tsx

Test plan

Checklist

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[mattcen]

Nice work on this! Just build a version with this merged in and it coped fine with the simple Google Doc I threw at it! Thanks for your efforts!