Handle DataValidationError notifications returned by ConvertBack (#22171)

* Handle DataValidationError notifications returned by ConvertBack

A converter returning a BindingNotification with DataValidationError fell
through to the target type converter, which replaced it with a cast error
that stringified the notification. Publish the original error instead.

* Add additional failing tests.

There are more `BindingNotification` cases to handle.

* Handle the other `BindingNotification` cases.

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Co-authored-by: grokys <grokys@users.noreply.github.com>