KT-9670: optimize Class <-> KClass wrapping/unwrapping as a special case of boxing/unboxing.

NB doesn't work for arrays of classes.

compiler/testData/codegen/bytecodeText/boxingOptimization/kClassInAnnotation.kt

@@ -0,0 +1,16 @@
+import kotlin.reflect.KClass
+
+@Retention(AnnotationRetention.RUNTIME)
+annotation class Ann(val arg: KClass<*>)
+
+class OK
+
+@Ann(OK::class) class MyClass
+
+fun test(): String {
+    val arg = MyClass::class.java.getAnnotation(Ann::class.java).arg.java
+    return arg.getSimpleName()
+}
+
+// 0 INVOKESTATIC kotlin/jvm/internal/Reflection\.getOrCreateKotlinClass
+// 0 INVOKESTATIC kotlin/jvm/JvmClassMappingKt\.getJavaClass