Simplify Toolbox Icon naming

Since, we only use the same Root Namespace for all controls, we don't need to specify them.

build/Windows.Toolkit.VisualStudio.Design.props

@@ -17,7 +17,7 @@
   <ItemGroup>
     <AppDesigner Include="Properties\"/>
       <!-- The 'LogicalName' metadata changes the default manifest naming scheme -->
-    <EmbeddedResource Include="Icons\$(ParentProjectName).*.icon.png" LogicalName="$(ParentProjectRootNamespace).%(Filename)%(Extension)"/>
+    <EmbeddedResource Include="Icons\*.icon.png" LogicalName="$(ParentProjectRootNamespace).%(Filename)%(Extension)"/>
     <EmbeddedResource Include="$(ParentProjectOutputPath)$(ParentProjectName).xml" LinkBase="Properties\" LogicalName="%(Filename)%(Extension)"/>
   </ItemGroup>