Use PublicApiAnalyzer instead of a (broken) unit test

Author: sharwell

StyleCop.Analyzers/Directory.Build.props

@@ -49,6 +49,16 @@
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.CodeStyle" Version="2.11.0-beta2-63603-03" PrivateAssets="all" />
   </ItemGroup>
 
+  <!-- Public API -->
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" Version="2.9.7" PrivateAssets="all" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <AdditionalFiles Include="PublicAPI.Shipped.txt" Condition="Exists('PublicAPI.Shipped.txt')" />
+    <AdditionalFiles Include="PublicAPI.Unshipped.txt" Condition="Exists('PublicAPI.Unshipped.txt')" />
+  </ItemGroup>
+
   <ItemGroup>
     <None Include="$(MSBuildThisFileDirectory)*.ruleset" Link="%(Filename)%(Extension)" />
 

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/DocumentationRules/PropertySummaryDocumentationCodeFixProvider.cs

@@ -21,7 +21,7 @@ namespace StyleCop.Analyzers.DocumentationRules
     /// </summary>
     [ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(PropertySummaryDocumentationCodeFixProvider))]
     [Shared]
-    public class PropertySummaryDocumentationCodeFixProvider : CodeFixProvider
+    internal class PropertySummaryDocumentationCodeFixProvider : CodeFixProvider
     {
         /// <inheritdoc/>
         public override ImmutableArray<string> FixableDiagnosticIds { get; } =