Use RegisterImplementationSourceOutput for perf

Author: koenbeuk

src/EntityFrameworkCore.Projectables.Generator/ProjectionExpressionGenerator.cs

@@ -51,7 +51,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
                 = context.CompilationProvider.Combine(memberDeclarations.Collect());
 
             // Generate the source using the compilation and enums
-            context.RegisterSourceOutput(compilationAndEnums,
+            context.RegisterImplementationSourceOutput(compilationAndEnums,
                 static (spc, source) => Execute(source.Item1, source.Item2, spc));
         }