ObjectCreationInitializer completion doesn't escape keywords

```c#
class C
{
   int @new { get; set; }
   void M()
   {
        _ = new C() { $$ }; // "@new" should be offered, but "new" is offered instead.
   }
}
```

Follow-up on comment made in https://github.com/dotnet/roslyn/pull/26474 about a related provider.