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/kClassInAnnotationEscaping.kt

@@ -0,0 +1,20 @@
+import kotlin.reflect.KClass
+
+@Retention(AnnotationRetention.RUNTIME)
+annotation class Ann(val arg: KClass<*>)
+
+class OK
+
+@Ann(OK::class) class MyClass
+
+var escape: KClass<*>? = null
+
+fun test1(): String {
+    val arg = MyClass::class.java.getAnnotation(Ann::class.java).arg
+    escape = arg
+    val argSimpleName = arg.java.getSimpleName()
+    return argSimpleName
+}
+
+// 1 INVOKESTATIC kotlin/jvm/internal/Reflection\.getOrCreateKotlinClass
+// 1 INVOKESTATIC kotlin/jvm/JvmClassMappingKt.getJavaClass