Suppress RS1041 analyzer rule (#97374)

* Suppress RS1041 analyzer rule

* Update JsonSourceGenerator.Roslyn4.0.cs

* Update Generator.cs

eng/generatorProjects.targets

@@ -3,6 +3,10 @@
   <PropertyGroup>
     <GeneratorProjectBaseTargetPath>analyzers/dotnet</GeneratorProjectBaseTargetPath>
     <GeneratorProjectBaseTargetPath Condition="'$(AnalyzerLanguage)' != ''">$(GeneratorProjectBaseTargetPath)/$(AnalyzerLanguage)</GeneratorProjectBaseTargetPath>
+
+    <!-- RS1041: Compiler extensions should be implemented in assemblies targeting netstandard2.0.
+         Runtime intentionally targets .NETCoreApp for nullable annotation warnings without shipping. -->
+    <NoWarn Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">$(NoWarn);RS1041</NoWarn>
   </PropertyGroup>
 
   <ItemDefinitionGroup>

src/libraries/Microsoft.Extensions.Options/gen/Generator.cs

@@ -12,9 +12,7 @@ using Microsoft.CodeAnalysis.Text;
 
 namespace Microsoft.Extensions.Options.Generators
 {
-#pragma warning disable RS1041 // we're multi-targeting so this is fine
     [Generator]
-#pragma warning restore
     public class OptionsValidatorGenerator : IIncrementalGenerator
     {
         public void Initialize(IncrementalGeneratorInitializationContext context)

src/libraries/System.Text.Json/gen/JsonSourceGenerator.Roslyn4.0.cs

@@ -16,9 +16,7 @@ namespace System.Text.Json.SourceGeneration
     /// <summary>
     /// Generates source code to optimize serialization and deserialization with JsonSerializer.
     /// </summary>
-#pragma warning disable RS1041 // we're multi-targeting so this is fine
     [Generator]
-#pragma warning restore
     public sealed partial class JsonSourceGenerator : IIncrementalGenerator
     {
 #if ROSLYN4_4_OR_GREATER