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

compiler/testData/codegen/light-analysis/innerNested/createdNestedInOuterMember.txt

@@ -1,14 +1,17 @@
+@kotlin.Metadata
 public final class CreatedNestedInOuterMemberKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
     public final static method foo(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1): int
 }
 
+@kotlin.Metadata
 public final class Outer {
     inner class Outer/Nested
     public method <init>(): void
     public final @org.jetbrains.annotations.NotNull method bar(): java.lang.String
 }
 
+@kotlin.Metadata
 public final static class Outer/Nested {
     private final field y: int
     inner class Outer/Nested