Show ES request previews in Watcher #42796
Description
Note that even though the "Create Advanced Watch" form allows the user to edit the payload, having a dedicated flyout for the entire endpoint and payload will make it easier for the user to copy and paste. We should also offer a "Copy to clipboard" button, so the user could copy and paste this into Console, and add some text that explains what the user is looking at:
This is the underlying request to Elasticsearch that will {create/update} this watch.