Stretch content horizontally in ListViewItem

[robloo]

Description

Content in ListViewItem is not horizontally stretched by default. Instead, the content is left aligned. This makes content appear as shown in the top image instead of the expected bottom image below (taken from #1402)

This PR changes the horizontal alignment to Stretch from Left. Risks of this change should be quite low since it's only changing the container style (ListViewItem itself) #1402 (comment)

The original behavior (Left alignment) is different from older XAML technologies such as WPF and is counterintuitive for application developers. It prevents doing something such as what is below unless the ItemContainerStyle is overridden:

<ListView>
  <ListView.ItemContainerStyle>
    <Style TargetType="ListViewItem">
        <Setter Property="HorizontalContentAlignment"
                Value="Stretch" />
    </Style>
  </ListView.ItemContainerStyle>
</ListView>

The reasons for switching may have been due to the prevalence of horizontal scrolling in ListViews when UWP/Metro styling first came around.

Motivation and Context

Closes #1402
Closes #3682

How Has This Been Tested?

Screenshots (if appropriate):

[robloo]

An open question is whether ListPickerFlyoutPresenterItemStyle should be updated as well.

[ranjeshj]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mdtauk]

Is there any consideration needed for other list views, like GridView or SemanticZoom controls?

[ranjeshj]

An open question is whether ListPickerFlyoutPresenterItemStyle should be updated as well.

Interesting. I don't see this style being used anywhere. @YuliKl do you know where this style is used ?

[ranjeshj]

Is there any consideration needed for other list views, like GridView or SemanticZoom controls?

I don't think this is very interesting for GridView. SemanticZoom just uses ListView/GridView inside them.