Need a way to enable `isSupportRangeFeature` for Avalonia

[ptasev]

I believe Avalonia supports CollectionChanged events when there is more than one item in the NotifyCollectionChangedEventArgs NewItems/OldItems. I tested by running the sample app, and setting isSupportRangeFeature to true during debugging.

ObservableCollections/src/ObservableCollections/SynchronizedViewList.cs

Line 572 in b715f56

if (isSupportRangeFeature)

I put a breakpoint there so I can modify the value of isSupportRangeFeature before pressing continue.

Since the extension methods ToNotifyCollectionChanged and the writeable version don't have a way to set this value, and NonFilteredSynchronizedViewList is internal there appears to be no way to enable this feature programmatically.

I guess this makes it a little awkward that NotifyCollectionChangedSynchronizedViewList doesn't have the *Range methods because WPF doesn't support it, but Avalonia does.