FSE: Coding standards: DOCTYPE should be the first line/character of any HTML document

[audrasjb]

Description

On Twenty Twenty-Two, I spotted that the DOCTYPE of HTML pages is generated after an empty line.
According to the HTML specification/living standard, the DOCTYPE should be the very first element of the document.

How has this been tested?

Using Twenty Twenty-Two Full site editing templates.

Types of changes

That's a small fix 😊

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• [] My code has proper inline documentation.
• [] I've included developer documentation if appropriate.
• [] I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).