Set GitHubActionLink.Opacity on disabled.

Sigh. Seems that hyperlinks don't respect dependency property precedence, so the `IsEnabled=False` trigger for `Hyperlink.Foreground` doesn't override the foreground `TemplateBinding`. Not sure what we can do here other than set the control's opacity when disabled, so that's what we'll do for now.

Author: grokys

src/GitHub.VisualStudio.UI/Styles/GitHubActionLink.xaml

@@ -13,6 +13,15 @@
       <Setter.Value>
         <ControlTemplate TargetType="{x:Type ui:GitHubActionLink}">
           <TextBlock TextTrimming="{TemplateBinding TextTrimming}" TextWrapping="{TemplateBinding TextWrapping}">
+            <TextBlock.Style>
+              <Style TargetType="TextBlock">
+                <Style.Triggers>
+                  <Trigger Property="IsEnabled" Value="False">
+                    <Setter Property="Opacity" Value="0.5"/>
+                  </Trigger>
+                </Style.Triggers>
+              </Style>
+            </TextBlock.Style>
             <Hyperlink Command="{TemplateBinding Command}"
                        CommandParameter="{TemplateBinding CommandParameter}"
                        Foreground="{TemplateBinding Foreground}">
@@ -40,8 +49,7 @@
                       </MultiTrigger.Setters>
                     </MultiTrigger>
                     <Trigger Property="IsEnabled" Value="False">
-                        <Setter Property="Foreground" Value="{StaticResource GHBlueLinkButtonDisabledBrush}"/>
-                        <Setter Property="TextDecorations" Value="None" />
+                      <Setter Property="TextDecorations" Value="None" />
                     </Trigger>
                   </Style.Triggers>
                 </Style>