Missing config attribute "promotion" #58
Description
According to the docs (https://www.tiny.cloud/docs/tinymce/latest/customize-ui/#premium-upgrade-promotion-option) promotion should be configurable, but currently isn't as a WebComponent. I think the fix should be to add the attribute to configAttributes in tinymce/tinymce-webcomponent/src/main/ts/component/Editor.ts. I might make a MR later unless that is intended to be non-configurable.