fix: mark nocookie youtube url as valid when parsing html

[LukasHirt]

Please describe your changes

Extended the YOUTUBE_REGEX in youtube extension to consider nocookie URL as valid.

How did you accomplish your changes

Added youtube-nocookie\.com into the regex.

How have you tested your changes

Locally via link to my app and added automated tests.

How can we verify your changes

Set content of the editor to e.g.

<div data-youtube-video=""><iframe class="w-full aspect-video" width="640" height="480" allowfullscreen="true" autoplay="false" disablekbcontrols="false" enableiframeapi="false" endtime="0" ivloadpolicy="0" loop="false" modestbranding="false" origin="" playlist="" src="https://www.youtube-nocookie.com/embed/dh72Dz0OqLk" start="0"></iframe></div>

Remarks

[add any additional remarks here]

Checklist

• The changes are not breaking the editor
• Added tests where possible
• Followed the guidelines
• Fixed linting issues

Related issues

[add a link to the related issues here]

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[bdbch]

LGTM