NumericUpDown - Changes to FormatString are not reflected immediately

[pokorpa]

Describe the bug

When FormatString binding value is changed, the new format is applied only after focusing or interacting with the control.

To Reproduce

1. Create NumericUpDown with binding to FormatString.
2. Change bound value
3. The content of NumericUpDown stays the same.

Expected behavior

Content of NumericUpDown changes accoring to the new format string immediately.

Avalonia version

11.1.1

OS

Windows 10

Additional context

I believe that the problem is in SyncTextAndValueProperties call in OnFormatStringChanged.
The call should set forceTextUpdate=true, ie.

protected virtual void OnFormatStringChanged(string? oldValue, string? newValue)
{
    if (IsInitialized)
    {
        SyncTextAndValueProperties(false, null, true);
    }
}

[pokorpa]

Created PR #16575 with proposed fix.