Make `unevaluatedProperties` error message as clear as `additionalProperties` message

[plocket]

The additionalProperties error message names the additional property: Property arbitrary_key is not expected to be here.

The unevaluatedProperties error message doesn't: unevaluatedProperties must NOT have unevaluated properties. It also shows the wrong line number - it's the line for the containing object, not for the property itself.

Is it possible to make the second more like the first? It was a really useful message.