Large XML docs take up all quick info flyout space and (1) get clipped with no scrolling, and (2) hide all diagnostics

[Sergio0694]

Version Used: VS 17.12

Steps to Reproduce:

1. Use this preview feed
2. Create a blank WinUI 3 app
3. Reference Community Toolkit version 8.4.0-build.43 or later
4. Set PublishAot to true
5. Add the following code:

public partial class MyViewModel : ObservableObject
{
    [ObservableProperty]
    private int number;
}

6. Hover on the diagnostic that will show up on the attribute.

Expected Behavior:

The quick info window should be scrollable, so that you can always read all its content. Ideally, it'd also have reserved space at the bottom (like a footer) so that no matter how long the XML docs are, you can always see the list of diagnostics at that location at the bottom of the flyout.

Personally I'd much prefer a solution with a fixed footer, so diagnostics are always visible at a glance, without needing to scroll.

cc. @sharwell

Actual Behavior: