Allow generating observable properties with private setters

[mikernet]

Overview

Would be nice if you could generate observable properties with private setters. Many observable properties should only be privately settable.

API breakdown

Add the following property to ObservablePropertyAttribute:

public bool PrivateSetter { get; set; }

Usage example

public partial class MyViewModel : ObservableObject
{
    [ObservableProperty(PrivateSetter = true)]
    private bool _isLoaded;

    public async Task LoadAsync()
    {
        Data = await ...;
        IsLoaded = true;
    }
}

Breaking change?

No

Alternatives

None

Additional context

No response

Help us help you

No, just wanted to propose this

[Sergio0694]

Duplicate of #291.
Superseded by #555.