Enable PlatformCompatibilityAnalyzer for RCL projects (#25636)

Author: mkArtakMSFT

src/ProjectTemplates/Web.ProjectTemplates/RazorClassLibrary-CSharp.csproj.in

@@ -9,6 +9,10 @@
   <ItemGroup Condition="'$(SupportPagesAndViews)' == 'True'">
     <FrameworkReference Include="Microsoft.AspNetCore.App" />
   </ItemGroup>
+  
+  <ItemGroup Condition="'$(SupportPagesAndViews)' == 'False'">
+    <SupportedPlatform Include="browser" />
+  </ItemGroup>
 
   <ItemGroup Condition="'$(SupportPagesAndViews)' != 'True'">
     <PackageReference Include="Microsoft.AspNetCore.Components.Web" Version="${MicrosoftAspNetCoreComponentsWebPackageVersion}" />