Use the iframe-less CKEditor in the standalone WYSIWYG edit mode

The standalone WYSIWYG edit mode (edit action, page creation, TextArea properties, comments) uses an iframe-based CKEditor, while the in-place edit mode uses an iframe-less one. The iframe causes several usability issues:

• Macros that rely on JavaScript, such as Live Data, are not rendered properly and are not interactive while editing.
• The edited content does not look and behave like in view mode or in in-place edit mode.
• Enabling the "Load JavaScript Skin Extensions" configuration only partially helps and can even prevent the editor from loading (XWIKI-23338).

Proposal

Use the iframe-less CKEditor in the standalone WYSIWYG edit mode too, as in in-place edit mode. The edited content then gets the same styles and scripts as in view mode. This is also a step towards dropping the standalone WYSIWYG edit mode entirely. BlockNote already works this way in both edit modes.

The "Load JavaScript Skin Extensions" configuration becomes useless once this is done (see XWIKI-22781).