Picker Title displays above the control on Windows

### Description

When running on Windows, the `Picker` displays the `Title` property above the control. According to the documentation, and the behaviour on Android, I expect it to be treated as a placeholder when no item is selected.

[Documentation](https://docs.microsoft.com/en-us/dotnet/maui/user-interface/controls/frame) snippet:

Windows:

Android:

### Steps to Reproduce

1. Create new MAUI app.
2. Add a `Picker` to `MainPage.xaml` as below (direct copy from[ Microsoft's sample code](https://docs.microsoft.com/en-us/dotnet/maui/user-interface/controls/picker#set-the-itemssource-property))
```

Baboon
Capuchin Monkey
Blue Monkey
Squirrel Monkey
Golden Lion Tamarin
Howler Monkey
Japanese Macaque

```
3. Run on `Windows Machine`

### Version with bug

Release Candidate 2 (current)

### Last version that worked well

Unknown/Other

### Affected platforms

Windows

### Affected platform versions

Windows 10 (21H2 | 19044.1645)

### Did you find any workaround?

No

### Relevant log output

```shell
N/A
```

Start with the Picker declared in MainPage.xaml using the documented ItemsSource sample, and reproduce it on a Windows Machine. Compare the Windows result with the documented and Android behavior; done means an unselected Picker treats its Title as a placeholder rather than displaying it above the control.

Written by the indexing model from the issue text.