FEAT: Add support for promises to custom RTE API

What are you trying to add to GrapesJS? Support for richtext editors with promise based APIs.

Describe your feature request detailed CKEditor5's Editor.create and Editor.destroy methods return a Promise that resolves when the editor has been fully created or destroyed. This causes an issue when destroying the editor (when you finish editing a component) because GrapesJS syncs the changes to the model before the Editor.destroy promise has resolved which causes CKEditor HTML to be written to the model.

As a workaround you can sync the content again after the promise has resolved but it would be cleaner if the API supported promises.

We could add this in a backward compatible way be checking if the return values of the RTE's enable and disable methods are thennable and, if so, wait for the promise to resolve before continuing.

Is this something GrapesJS would consider supporting?

Is there an alternative at the latest version? No

Is this related to an issue? https://github.com/artf/grapesjs/issues/1516 https://github.com/artf/grapesjs/issues/1236