nameonly should not constrain default values

[seebees]

Dafny version

3.13

Code to produce this issue

datatype Foo = Foo(
  nameonly bar: Option<string> := None,
  nameonly baz: Option<string>
)


This is probably because `Foo("positional parameters", "have order")`.
However `nameonly` means that I MUST

```dafny
Foo(
  baz := "Look ma, no order!"
)

### Command to run and resulting output

_No response_

### What happened?

In the above example `baz` gets:
`a required parameter must precede all optional parameters`

### What type of operating system are you experiencing the problem on?

Mac