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

compiler/testData/codegen/light-analysis/reflection/classes/qualifiedName.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public final class Klass {
     public final static field Companion: Klass.Companion
     inner class Klass/Companion
@@ -5,16 +6,19 @@ public final class Klass {
     public method <init>(): void
 }
 
+@kotlin.Metadata
 public final static class Klass/Companion {
     inner class Klass/Companion
     private method <init>(): void
 }
 
+@kotlin.Metadata
 public final static class Klass/Nested {
     inner class Klass/Nested
     public method <init>(): void
 }
 
+@kotlin.Metadata
 public final class QualifiedNameKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }