Improve handling of nested HTML "a" tags in editor/preview mode to better align with frontend view, raise warning

Continuing the discussion from NO BUG: Editor shows layout correctly, but incorrect on frontend when block is set with 'a' HTML tag:

It’d really be great if we could get the editor and preview mode / frontend to look closer in line with each other when there are nested “a” HTML link tags. While I can appreciate why it looks fine in the editor but not the frontend due to needing to select elements in the editor, I believe the preview mode in Bricks can be greatly improved by allowing it to draw the page as a browser normally would, which would catch these types of discrepancies before they get published, allowing for a better workflow.

Alternatively in that particular scenario, at the very least a warning that catches those types of nested “a” HTML tags would be very helpful. For example, I noticed Breakdance has a caution message when changing an elements semantic HTML tag to “a”, perhaps adding something like this in Bricks would be helpful for others too.

Ideally though I’d really like to see the preview mode simply be improved to better align with what we expect the frontend to look like. Right now it seems like all preview does is get the editor elements out of the way but that means it won’t properly show issues in the preview mode that can’t be caught in the editor until it’s published already.