Additional data required for page_copies events

Apps can register webhooks for page_copied events. A use case exists where the app needs to access the copied page in order to query the original context and perhaps copy that if it is not included in the new page (e.g. page properties). However, the page_copied event does not include sufficient information to allow the app to access the original page. It is therefore suggested that the page_copied event payload be augmented with the ID of the page that was copied.