TokenizingTextBoxItem does only check for single character TokenDelimiter

### Describe the bug

`**TokenizingTextBoxItem.AutoSuggestBox.cs** `

**`AutoSuggestBox_TextChanged()`**

wrong
` bool lastDelimited = t[t.Length - 1] == Owner.TokenDelimiter[0];`

correct
`bool lastDelimited = t.EndsWith(Owner.TokenDelimiter);`

### Regression

_No response_

### Reproducible in sample app?

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

### Steps to reproduce

```text
no text
```

### Expected behavior

no text

### Screenshots

_No response_

### Windows Build Number

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

### Other Windows Build number

_No response_

### App minimum and target SDK version

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

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

_No response_

### Nuget packages

_No response_

### Additional context

_No response_

### Help us help you

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