Fix 53427; Change default UAP styling for a label

[kingces95]

Description of Change

Unexpected styling for UWP EntryCell label: https://bugzilla.xamarin.com/attachment.cgi?id=20400

The user expected the EntryCell label styling to match the SwitchCell label styling. EntryCell style is set here:

Xamarin.Forms/Xamarin.Forms.Platform.UAP/Resources.xaml

Line 427 in c65a9a8

<TextBlock Text="{Binding Label}" Style="{ThemeResource BaseTextBlockStyle}" Foreground="{Binding LabelColor, Converter={StaticResource ColorConverter}, ConverterParameter=SystemControlBackgroundChromeMediumLowBrush}" />

.

As you can see it sets Foreground="{Binding LabelColor, Converter={StaticResource ColorConverter}, ConverterParameter=SystemControlBackgroundChromeMediumLowBrush}".

This must have been added to allow coloring the label (prob to red to indicate validation error) however no other controls allow coloring the label -- just EntryCell. Which is fine but there is no precedent for the ConverterParameter. Currently its value is SystemControlBackgroundChromeMediumLowBrush but I think it should be DefaultTextForegroundThemeBrush.

Bugs Fixed

Bug https://bugzilla.xamarin.com/show_bug.cgi?id=53427

API Changes

None

Behavioral Changes

UAP EntryCell default label styling change.

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of master at time of PR
• Changes adhere to coding standard
• Consolidate commits as makes sense