Fix: Styles that are wrapped with editor styles wrapper are not cached

[jorgefilipecosta]

Fix: #18741

Description

Until now we passed the editor styles content via editor settings. The editor module transformed the CSS rules to wrap them and added them to a newly created style element on the page.
The current approach has two problems:

• The styles are not cached and they are passed as a set every time the editor loads.
• If the editor styles are pointing to a http(s) URL the server needs to download the styles on every page load to content before sending the styles to the client.

This PR proposes a different approach: Editor styles are enqueued to the client so they can be cached and the server does not need to download anything, as a setting we just pass the editor style URL's. On the client, we dynamically change the stylesheets to be correctly wrapped.

How has this been tested?

I checked the editor still looks as before.
Using the browser dev tools I checked the stylesheets were transformed as expected.

[jorgefilipecosta]

Closing this PR as the approach referred may have some problems in the core because the styles are concatenated there so isolating specific style sheets is not simple.