fix alphabetical ordering

Author: eiriktsarpalis

src/libraries/System.Text.Json/gen/System.Text.Json.SourceGeneration.targets

@@ -41,9 +41,9 @@
     <Compile Include="$(CommonPath)\Roslyn\GetBestTypeByMetadataName.cs" Link="Common\Roslyn\GetBestTypeByMetadataName.cs" />
     <Compile Include="ClassType.cs" />
     <Compile Include="CollectionType.cs" />
-    <Compile Include="JsonSourceGenerator.Emitter.ExceptionMessages.cs" />
     <Compile Include="JsonConstants.cs" />
     <Compile Include="JsonSourceGenerator.Emitter.cs" />
+    <Compile Include="JsonSourceGenerator.Emitter.ExceptionMessages.cs" />
     <Compile Include="JsonSourceGenerator.Parser.cs" />
     <Compile Include="ObjectConstructionStrategy.cs" />
     <Compile Include="ParameterGenerationSpec.cs" />