This commit refactors the website AceEditor to owl. The wrapper
around the lib was defined in web_editor, and extended in website,
where it was used (single usecase). This commit thus introduces an
owl Component to replace it, directly in website, and specialized
to the website usecase.
This thus allows to remove the legacy implementation.
This also removes the last usecase of Widget and select2 library
in the backend bundle, which will allow to trim it down.
Part of task~3439226
Part-of: odoo/odoo#139154