Make @SubclassOptInRequired accept multiple experimental markers

[2/5] Update SubclassOptInRequired argument type

Previously, @SubclassOptInRequired could not accept multiple
experimental markers and did not allow repeating the annotation.
This change allows the marker to be passed as a vararg.

^KT-70562 in progress

Author: BlondeHex

libraries/stdlib/src/kotlin/annotations/OptIn.kt

@@ -178,5 +178,5 @@ public annotation class ExperimentalSubclassOptIn
 @SinceKotlin("2.1")
 @WasExperimental(ExperimentalSubclassOptIn::class)
 public annotation class SubclassOptInRequired(
-    val markerClass: KClass<out Annotation>
+    vararg val markerClass: KClass<out Annotation>,
 )

libraries/tools/binary-compatibility-validator/klib-public-api/kotlin-stdlib.api

@@ -283,10 +283,10 @@ open annotation class kotlin/SinceKotlin : kotlin/Annotation { // kotlin/SinceKo
 }
 
 open annotation class kotlin/SubclassOptInRequired : kotlin/Annotation { // kotlin/SubclassOptInRequired|null[0]
-    constructor <init>(kotlin.reflect/KClass<out kotlin/Annotation>) // kotlin/SubclassOptInRequired.<init>|<init>(kotlin.reflect.KClass<out|kotlin.Annotation>){}[0]
+    constructor <init>(kotlin/Array<out kotlin.reflect/KClass<out kotlin/Annotation>>...) // kotlin/SubclassOptInRequired.<init>|<init>(kotlin.Array<out|kotlin.reflect.KClass<out|kotlin.Annotation>>...){}[0]
 
     final val markerClass // kotlin/SubclassOptInRequired.markerClass|{}markerClass[0]
-        final fun <get-markerClass>(): kotlin.reflect/KClass<out kotlin/Annotation> // kotlin/SubclassOptInRequired.markerClass.<get-markerClass>|<get-markerClass>(){}[0]
+        final fun <get-markerClass>(): kotlin/Array<out kotlin.reflect/KClass<out kotlin/Annotation>> // kotlin/SubclassOptInRequired.markerClass.<get-markerClass>|<get-markerClass>(){}[0]
 }
 
 open annotation class kotlin/Suppress : kotlin/Annotation { // kotlin/Suppress|null[0]

libraries/tools/binary-compatibility-validator/reference-public-api/kotlin-stdlib-runtime-merged.txt

@@ -237,7 +237,7 @@ public abstract interface annotation class kotlin/SinceKotlin : java/lang/annota
 }
 
 public abstract interface annotation class kotlin/SubclassOptInRequired : java/lang/annotation/Annotation {
-	public abstract fun markerClass ()Ljava/lang/Class;
+	public abstract fun markerClass ()[Ljava/lang/Class;
 }
 
 public abstract interface annotation class kotlin/Suppress : java/lang/annotation/Annotation {