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.