Use moveBefore when available to preserve DOM state

[mathieumahe]

Description

This PR updates the code to use the new moveBefore() method when it is available, and falls back to insertBefore() otherwise.

Unlike insertBefore(), moveBefore() allows moving a node without removing it from the DOM, which preserves its internal state and ongoing behavior.

This has several important benefits:

• Component state is preserved
• CSS animations are not reset
• Embedded content such as iframes is not reloaded (e.g. TinyMCE editors, YouTube videos, etc.)

References

MDN: Element.moveBefore()
https://developer.mozilla.org/en-US/docs/Web/API/Element/moveBefore#movebefore_constraints