Show label such as "New item" on new repeaters before fields are populated

[Toutouwai]

Short description of the enhancement

The "Repeater item labels" feature is great, but when in use it has the side-effect that the label for newly added repeater items often looks poorly formed because in a new item no field values are available yet.

So a format like this...

...comes out looking like this in the page editor...

It would be nice if there was an option to tell PW not to attempt to use the custom label format on new items and just label it "New item" or something like that.

It's probably possible to do this with a hook but it would be nice to have it built-in.