Alternate Row: ListviewBase always returns null

### Describe the bug

the code in "AlternateRow.cs":

`_itemsForList.TryGetValue(sender, out Windows.UI.Xaml.Controls.ListViewBase listViewBase);`
` if (listViewBase == null)
{
return;
}`

always returns null. this is why when adding items to an existing list never changes the items following the new one.

### Regression

_No response_

### Reproducible in sample app?

- [X] This bug can be reproduced in the sample app.

### Steps to reproduce

```text
create a list and add an alternate row background property.

insert an item or remove an item
```

### Expected behavior

when an item is added or removed from a list, all following items' background's should change. it does not

### Screenshots

_No response_

### Windows Build Number

- [X] Windows 10 1809 (Build 17763)
- [X] Windows 10 1903 (Build 18362)
- [X] Windows 10 1909 (Build 18363)
- [X] Windows 10 2004 (Build 19041)
- [X] Windows 10 20H2 (Build 19042)
- [X] Windows 10 21H1 (Build 19043)
- [X] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [X] Windows 10, version 1809 (Build 17763)
- [X] Windows 10, version 1903 (Build 18362)
- [X] Windows 10, version 1909 (Build 18363)
- [X] Windows 10, version 2004 (Build 19041)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

2022

### Visual Studio Build Number

Version 17.8.3

### Device form factor

Desktop

### Nuget packages

_No response_

### Additional context

_No response_

### Help us help you

Yes, I'd like to be assigned to work on this item.

Beginne in AlternateRow.cs und reproduziere das Problem in der Beispielanwendung, indem du Elemente aus einer Liste mit einem abwechselnden Zeilenhintergrund einfügst und entfernst. Verfolge, warum die ListViewBase-Suche null zurückgibt, und überprüfe anschließend, dass die Hintergründe aller nachfolgenden Elemente nach jeder Änderung aktualisiert werden.

Vom Indexierungsmodell aus dem Issue-Text verfasst.