SLC: force boxed return type when needed

e.g., when overriding a function whose return type is not primitive

^KT-57579 Fixed

analysis/analysis-api/src/org/jetbrains/kotlin/analysis/api/types/KtTypeMappingMode.kt

@@ -33,6 +33,11 @@ public enum class KtTypeMappingMode {
      */
     SUPER_TYPE_KOTLIN_COLLECTIONS_AS_IS,
 
+    /**
+     * When method return type should be boxed (e.g., kotlin.Int to Ljava/lang/Integer;)
+     */
+    RETURN_TYPE_BOXED,
+
     /**
      * Optimal mode to convert the return type of declarations if it's part of signature.
      */