[UWP][NavView] unable to scroll through expanded navigation items about uno.gallery

[Xiaoy312]

Removing the minimally customized NavigationView style worked.
---
On uwp, we were using nav-view from [email protected],
looking at the style from that package: lib\uap10.0\Microsoft.UI.Xaml\Themes
The style is slightly different than what we were using,
particularly the part where we have "ItemsContainerGrid"

Uno.Gallery/Uno.Gallery/Uno.Gallery.UWP/Views/Styles/NavigationView.xaml

Lines 1343 to 1396 in 628387e

	<Grid x:Name="ItemsContainerGrid"
	Grid.Row="6"
	Margin="0,0,0,8">
	<Grid.RowDefinitions>
	<RowDefinition x:Name="MenuItemsRow"
	Height="Auto"
	MinHeight="{ThemeResource NavigationViewItemOnLeftMinHeight}" />
	<!-- MenuItems -->
	<RowDefinition Height="*"
	MinHeight="21" />
	<!-- Fill spacing -->
	<RowDefinition Height="Auto" />
	<!-- PaneFooter -->
	<RowDefinition x:Name="FooterItemsRow"
	Height="Auto"
	MinHeight="{ThemeResource NavigationViewItemOnLeftMinHeight}" />
	<!-- FooterItems -->
	</Grid.RowDefinitions>
	<!-- MenuItems -->
	<muxc:ItemsRepeaterScrollHost HorizontalAlignment="Stretch"
	VerticalAlignment="Stretch">
	<ScrollViewer x:Name="MenuItemsScrollViewer"
	TabNavigation="Local"
	VerticalScrollBarVisibility="Auto">
	<!-- Left nav ItemsRepeater -->
	<muxc:ItemsRepeater x:Name="MenuItemsHost"
	AutomationProperties.Name="{TemplateBinding AutomationProperties.Name}"
	AutomationProperties.AccessibilityView="Content" />
	</ScrollViewer>
	</muxc:ItemsRepeaterScrollHost>
	<muxc:NavigationViewItemSeparator x:Name="VisualItemsSeparator"
	Grid.Row="1"
	VerticalAlignment="Center"
	Visibility="Collapsed"
	HorizontalAlignment="Stretch" />
	<!-- PaneFooter -->
	<ContentControl x:Name="FooterContentBorder"
	IsTabStop="False"
	VerticalContentAlignment="Stretch"
	HorizontalContentAlignment="Stretch"
	Grid.Row="2" />
	<!-- FooterItems -->
	<muxc:ItemsRepeaterScrollHost Grid.Row="3">
	<ScrollViewer x:Name="FooterItemsScrollViewer"
	contract7Present:VerticalAnchorRatio="1">
	<muxc:ItemsRepeater x:Name="FooterMenuItemsHost"
	AutomationProperties.AccessibilityView="Content" />
	</ScrollViewer>
	</muxc:ItemsRepeaterScrollHost>
	</Grid>

if we replace that section, with what they were using:

<muxc:ItemsRepeaterScrollHost Grid.Row="6"
                              Margin="0,0,0,20"
                              HorizontalAlignment="Stretch"
                              VerticalAlignment="Top">
    <ScrollViewer TabNavigation="Once"
                    VerticalScrollBarVisibility="Auto">
        <muxc:ItemsRepeater x:Name="MenuItemsHost"
                            AutomationProperties.Name="{TemplateBinding AutomationProperties.Name}"
                            AutomationProperties.AccessibilityView="Content">
            <muxc:ItemsRepeater.Layout>
                <muxc:StackLayout Orientation="Vertical" />
            </muxc:ItemsRepeater.Layout>
        </muxc:ItemsRepeater>
    </ScrollViewer>
</muxc:ItemsRepeaterScrollHost>

The scrollbar will start to appear.
---
Bumping that package to 2.5.0 also fixes this.