Replace with underscore code fix should not be proposed for class identifiers

This actually breaks the code:

https://github.com/dotnet/fsharp/assets/5451366/e30ed094-80cd-4518-87ca-f09a4eb79a07

```fsharp
type Animal(name:string) =
    member val Name = name with get, set

type Dog(name:string) as this = 
    inherit Animal(name)

    member this.Bark() =
        printfn "%s says Woof!" this.Name
```