Fix 3549: Forward relevant DPs to the nested Button (#3588)

* Forward relevant DPs to the nested Button

* Respect VerticalContentAlignment

* Respect SnapsToDevicePixels and UseLayoutRounding at root template element

Author: nicolaihenriksen

src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.SplitButton.xaml

@@ -39,6 +39,8 @@
           <Grid x:Name="OuterGrid"
                 Margin="{TemplateBinding Margin}"
                 Height="{TemplateBinding Height}"
+                SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
+                UseLayoutRounding="{TemplateBinding UseLayoutRounding}"
                 Width="{TemplateBinding Width}"
                 Effect="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(wpf:ElevationAssist.Elevation), Converter={x:Static converters:ShadowConverter.Instance}}">
             <Grid.ColumnDefinitions>
@@ -53,9 +55,18 @@
                     CommandParameter="{TemplateBinding CommandParameter}"
                     CommandTarget="{TemplateBinding CommandTarget}"
                     Content="{TemplateBinding Content}"
+                    ContentStringFormat="{TemplateBinding ContentStringFormat}"
+                    ContentTemplate="{TemplateBinding ContentTemplate}"
+                    ContentTemplateSelector="{TemplateBinding ContentTemplateSelector}"
+                    FontSize="{TemplateBinding FontSize}"
+                    FontFamily="{TemplateBinding FontFamily}"
+                    FontStretch="{TemplateBinding FontStretch}"
+                    FontStyle="{TemplateBinding FontStyle}"
+                    FontWeight="{TemplateBinding FontWeight}"
                     Height="{TemplateBinding Height}"
                     HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                     Style="{TemplateBinding ButtonStyle}"
+                    VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                     Padding="{TemplateBinding Padding}"
                     wpf:ElevationAssist.Elevation="Dp0"
                     wpf:ButtonAssist.CornerRadius="{TemplateBinding wpf:ButtonAssist.CornerRadius, Converter={StaticResource LeftButtonCornerRadiusConverter}}"/>
@@ -77,6 +88,7 @@
                         IsHitTestVisible="True"
                         Padding="{TemplateBinding Padding}"
                         Style="{TemplateBinding ButtonStyle}"
+                        VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                         wpf:ElevationAssist.Elevation="Dp0"
                         wpf:ButtonAssist.CornerRadius="{TemplateBinding wpf:ButtonAssist.CornerRadius, Converter={StaticResource RightButtonCornerRadiusConverter}}"
                         wpf:RippleAssist.IsDisabled="False"