Add a dedicated event type for SynchronizedView

[hadashiA]

What we would like to improve:

• Current ChangeKind only supports Add, Remove, Move; would like to add Replace, Reset events.
• ISynchronizedView event OnCollectionChanged comes from NotifyCollectionChangedEventArgs of the source collection, but it may not be sufficient.
  • NotifyCollectionChangedEventArgs indices may be different from the index of the view's collection
  • NotifyCollectionChangedEventArgs supports both single value/multiple value, which may be unwieldy for a public API.

So change parameters for SynchronizedView.OnCollectionChanged.

• Support for receiving recalculated indexes
• Support for receiving oldValue, etc.

Before:

void OnCollectionChanged(ChangedKind changedKind, T value,  TView view,   in NotifyCollectionChangedEventArgs<int> eventArgs);

After:

public readonly struct SynchronizedViewChangedEventArgs<T, TView>
{
    public readonly NotifyCollectionChangedAction Action = action;
    public readonly T NewValue = newValue;
    public readonly T OldValue = oldValue;
    public readonly TView NewView = newView;
    public readonly TView OldView = oldView;
    public readonly int NewViewIndex = newViewIndex;
    public readonly int OldViewIndex = oldViewIndex;
}

void OnCollectionChanged(in SynchronizedViewChangedEventArgs<int, ViewModel> eventArgs);