This reverts commit 5055bb7b.

Fixes #32111

Fixes #31801

Fixes #27797

Fixes #8488

**Bug**
Currently there is no indication in the markdown preview when a `markdown.styles` element fails to load

**Fix**
Show an alert then a stylesheet does not load

* Capture right parenthesis as part of url

* Update markdown link pattern

* Fix link highlighting when there is nested img and link href

Fixes #24808

**bug**
Markdown preview updates when you zoom. The root cause is that previews are updated whenever the config is changed.

**Fix**
Extract preview config to its own well defined object. Only update the preview when the keys we care about in the config change