Codesample plugin: consider import from CKE5 markup

[indigoxela]

Moved here from https://github.com/backdrop-contrib/tinymce_codehighlight/issues

As usual, the editors do their own thing. Very close, but not compatible. 😜

CKEditor 5 code block plugin:

<pre><code class="language-XXXX">...

TinyMCE codesample plugin:

<pre class="language-XXXX><code>...

It would be possible (in theory, didn't try) to add some import (eventually export) magic to make toggling between these two editors easier, but is it worth it? It's some effort (editor.parser / editor.serializer...) and might be unnecessary...

Prism.js can handle both variants, BTW.