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

compiler/testData/codegen/light-analysis/enum/abstractMethodInEnum.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public abstract enum class A {
     public final static field ENTRY: A
     inner class A/ENTRY
@@ -7,12 +8,14 @@ public abstract enum class A {
     public static method values(): A[]
 }
 
+@kotlin.Metadata
 final static class A/ENTRY {
     inner class A/ENTRY
     method <init>(p0: java.lang.String, p1: int): void
     public @org.jetbrains.annotations.NotNull method t(): java.lang.String
 }
 
+@kotlin.Metadata
 public final class AbstractMethodInEnumKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
     public final static @org.jetbrains.annotations.NotNull method f(@org.jetbrains.annotations.NotNull p0: A): java.lang.String