NewPropertyChangedEvent on ObservableObject

### Overview

I want to get the old value and the new value in the event

### API breakdown

```csharp
namespace CommunityToolkit.Mvvm.ComponentModel;
public abstract class ObservableObject
{
protected bool SetProperty(
[NotNullIfNotNull(nameof(newValue))] ref T field,
T newValue,
[CallerMemberName] string? propertyName = null
)
{
if (EqualityComparer.Default.Equals(field, newValue))
{
return false;
}

OnPropertyChanging(propertyName);

var oldValue = field;
if (AnotherPropertyChanging is not null)
AnotherPropertyChanging?.Invoke(this, new(propertyName, oldValue, newValue));

field = newValue;

OnPropertyChanged(propertyName);

if (AnotherPropertyChanged is not null)
AnotherPropertyChanged?.Invoke(this, new(propertyName, oldValue, newValue));

return true;
}

public event AnotherPropertyChangingEventHandler? AnotherPropertyChanging;
public event AnotherPropertyChangedEventHandler? AnotherPropertyChanged;
}

public delegate void AnotherPropertyChangingEventHandler(
object sender,
AnotherPropertyChangingEventArgs e
);
public delegate void AnotherPropertyChangedEventHandler(
object sender,
AnotherPropertyChangedEventArgs e
);

public class AnotherPropertyChangingEventArgs : PropertyChangingEventArgs
{
public object? OldValue { get; }

public object? NewValue { get; }

public AnotherPropertyChangingEventArgs(
string? propertyName,
object? oldValue,
object? newValue
)
: base(propertyName)
{
OldValue = oldValue;
NewValue = newValue;
}
}

public class AnotherPropertyChangedEventArgs : PropertyChangedEventArgs
{
public object? OldValue { get; }

public object? NewValue { get; }

public AnotherPropertyChangedEventArgs(string? propertyName, object? oldValue, object? newValue)
: base(propertyName)
{
OldValue = oldValue;
NewValue = newValue;
}
}
```

### Usage example

```csharp
public partial class MainWindowViewModel : ObservableObject
{
AnotherViewModel anotherViewModel = new();

[ObservableProperty]
private int _oldValue = 0;

[ObservableProperty]
private int _newValue = 0;

public MainWindowViewModel()
{
anotherViewModel.AnotherPropertyChanged += (s, e) =>
{
if (e.PropertyName == nameof(AnotherViewModel .Value))
{
OldValue = e.OldValue;
NewValue = e.NewValue;
}
};
}
}

public partial class AnotherViewModel : ObservableObject
{
[ObservableProperty]
private int _value = 0;
}
```

### Breaking change?

No

### Alternatives

Currently I'm using reflection to get the old value, but that's a very bad.
```csharp
protected override void OnPropertyChanging(PropertyChangingEventArgs e)
{
base.OnPropertyChanging(e);
if (AnotherPropertyChanged is not null)
{
_oldValue = this.GetType().GetProperty(propertyName).GetValue(this);
}
}
```

### Additional context

_No response_

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