Kapt3: Write stub class files with metadata (needed for incremental compilation)

compiler/testData/codegen/light-analysis/callableReference/bound/equals/reflectionReference.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public final class C {
     private final field bar: int
     public method <init>(): void
@@ -5,6 +6,7 @@ public final class C {
     public final method getBar(): int
 }
 
+@kotlin.Metadata
 public final class ReflectionReferenceKt {
     private final static @org.jetbrains.annotations.NotNull field C_bar: kotlin.reflect.KProperty1
     private final static @org.jetbrains.annotations.NotNull field C_barReflect: kotlin.reflect.KProperty1